[webview_flutter] Add webview_flutter_tizen package

* This PR is created from the PR below:
2bfc038 [webview_flutter] Update README and pubspec (#53)
bdd6a15 [webview_flutter] Enable intergation test (#52)
18da2a6 [webview_flutter] Update code by flutter version-up (#49)
1b6eeed [webview_flutter] Handle CompositionEvent (#47)
791511e [webview_flutter] Optimize tbm allocation (#42)
7059ce2 [webview_flutter] Add cookie and scroll APIs (#40)
c5a8930 Add some APIs (#37)
3feae1d [webview_flutter] Add NavigationDelegate and onWebResourceError (#36)
42b63f8 [webview_flutter] Add removeJavascriptChannels API and Callbacks (#31)
749930e [webview_flutter] Update LWE (#28)
9e26386 [webview_flutter] Implement addJavascriptChannels() (#27)
6a34ae0 [webview_flutter] Update LWE (#26)
a438093 [webview_flutter] Add evaluateJavascript() function (#25)
0d2c271 [webview_flutter] Update webview to be focused (#19)
b02b245 Enable IMF on Webview (#17)
571fa4a [webview_flutter_dev] Change webview interface && embedding lwe.so file (#15)
3413964 [webview_flutter_dev] Enable gl compositor at LWE (#14)
e988cf0 Change method name's first letter (#13)
cb8ee9b Handle key events for tizen webview (#11)
44987de [webview_flutter] Add webview_flutter initial package (#7)

Co-authored-by: MuHong Byun <mh.byun@samsung.com>
Co-authored-by: Seungsoo Lee <seungsoo47.lee@samsung.com>

packages/webview_flutter/.gitignore

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+.DS_Store
+.dart_tool/
+
+.packages
+.pub/
+
+build/

packages/webview_flutter/.metadata

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+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: 8b3760638a189741cd9ca881aa2dd237c1df1be5
+  channel: unknown
+
+project_type: plugin

packages/webview_flutter/CHANGELOG.md

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+## 0.0.1
+
+* TODO: Describe initial release.

packages/webview_flutter/LICENSE

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+Copyright (c) 2020 Samsung Electronics Co., Ltd. All rights reserved.
+Copyright (c) 2017 The Chromium Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+    * Neither the names of the copyright holders nor the names of the
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

packages/webview_flutter/README.md

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+# webview_flutter_tizen
+
+The Tizen implementation of [`webview_flutter`](https://github.com/flutter/plugins/tree/master/packages/webview_flutter).
+
+## Supported devices
+
+This plugin is available on these types of devices:
+
+- Galaxy Watch or TV (running Tizen 5.5 or later)
+
+## Usage
+
+```yaml
+dependencies:
+  webview_flutter: ^1.0.6
+  webview_flutter_tizen: ^1.0.0
+```
+
+To enable tizen implementation, set `WebView.platform = TizenWebView();` in `initState()`.
+For example:
+
+```dart
+import 'dart:io';
+
+import 'package:webview_flutter/webview_flutter.dart';
+import 'package:webview_flutter_tizen/webview_flutter_tizen.dart';
+
+class WebViewExample extends StatefulWidget {
+  @override
+  WebViewExampleState createState() => WebViewExampleState();
+}
+
+class WebViewExampleState extends State<WebViewExample> {
+  @override
+  void initState() {
+    super.initState();
+    WebView.platform = TizenWebView();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return WebView(
+      initialUrl: 'https://flutter.dev',
+    );
+  }
+}
+```
+
+## Limitations
+- This plugin is only supported on **Galaxy Watch and TV** devices running Tizen 5.5 or later.
+- This is an initial webview plugin for Tizen and is implemented based on Tizen Lightweight Web Engine (LWE). If you would like to know detailed specifications that the LWE supports, please refer to the following link :
+https://review.tizen.org/gerrit/gitweb?p=platform/upstream/lightweight-web-engine.git;a=blob;f=docs/Spec.md;h=ecb8f437c5a1facc77d3435e1a8aad6a267f12f3;hb=refs/heads/tizen

packages/webview_flutter/example/.gitignore

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+# Miscellaneous
+*.class
+*.log
+*.pyc
+*.swp
+.DS_Store
+.atom/
+.buildlog/
+.history
+.svn/
+
+# IntelliJ related
+*.iml
+*.ipr
+*.iws
+.idea/
+
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
+
+# Flutter/Dart/Pub related
+**/doc/api/
+**/ios/Flutter/.last_build_id
+.dart_tool/
+.flutter-plugins
+.flutter-plugins-dependencies
+.packages
+.pub-cache/
+.pub/
+/build/
+
+# Web related
+lib/generated_plugin_registrant.dart
+
+# Symbolication related
+app.*.symbols
+
+# Obfuscation related
+app.*.map.json

packages/webview_flutter/example/.metadata

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+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: 8b3760638a189741cd9ca881aa2dd237c1df1be5
+  channel: unknown
+
+project_type: app

packages/webview_flutter/example/README.md

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+# webview_flutter_tizen_example
+
+Demonstrates how to use the webview_flutter_tizen plugin.
+
+## Getting Started
+
+This project is a starting point for a Flutter application.
+
+A few resources to get you started if this is your first Flutter project:
+
+- [Lab: Write your first Flutter app](https://flutter.dev/docs/get-started/codelab)
+- [Cookbook: Useful Flutter samples](https://flutter.dev/docs/cookbook)
+
+For help getting started with Flutter, view our
+[online documentation](https://flutter.dev/docs), which offers tutorials,
+samples, guidance on mobile development, and a full API reference.