Update FileDropzone API (#678)

Adds new arguments `@queue` and `@filter` to FileDropzone.

Includes basic test coverage of these new APIs while deprecated API tests still pass.

Adds typing to FileDropzone component and DataTransferWrapper internal utility. I could have taken this further but I think it's good to do this process incrementally. Honestly there's a lot to untangle in some of these internal utilities (regarding typing support).

Registers/unregisters the FileDropzone as an event listener on the queue in the method from #654.

Also drops interim file-filtering techniques (in onDrop and onSelect). Closes #679

docs/validation.md

@@ -10,29 +10,24 @@ For more details see the [MDN accept attribute reference](https://developer.mozi
 
 ## Custom validation
 
-Both components provide callback arguments with which you may implement custom validation of chosen files.
+Both `<FileUpload>` and `<FileDropzone>` components accept the `@filter` argument with which you may implement custom validation of chosen files.
 
-`<FileUpload>` may be passed `@onSelect` and `<FileDropzone>` may be passed `@onDrop`.
-
-These are called *after* files have been chosen and *before* `@onFileAdd` is called by the queue.
-
-To implement validation, you may (optionally) return a subset of files from these callbacks to restrict which files are queued for upload.
+This are called *after* files have been chosen and *before* `fileAdded` is called by the queue.
 
 See the example below where the same validation callback is used for both selection methods.
 
 Commonly validated file properties are `type`, `name` and `size`. For more details see the [MDN File reference](https://developer.mozilla.org/en-US/docs/Web/API/File).
 
 ```hbs
 <FileDropzone
-  @name="photos"
-  @onDrop={{this.validateFiles}}
-  as |dropzone queue|
+  @queue={{queue}}
+  @filter={{this.validateFile}}
+  as |dropzone|
 >
   ...
   <FileUpload
-    @name="photos"
-    @onSelect={{this.validateFiles}}
-    @onFileAdd={{perform this.uploadImage}}
+    @queue={{queue}}
+    @filter={{this.validateFile}}
   />
   ...
 </FileDropzone>
@@ -50,8 +45,8 @@ const allowedTypes = [
 
 export default class ExampleComponent extends Component {
   ...
-  validateFiles(files) {
-    return files.filter((file) => allowedTypes.includes(file.type));
+  validateFile(file) {
+    return allowedTypes.includes(file.type);
   }
 }
 ```

ember-file-upload/addon/components/file-dropzone.hbs

@@ -6,12 +6,7 @@
     dragover=this.didDragOver
     drop=this.didDrop
   }}
-  {{update-queue
-    this.queue
-    multiple=@multiple
-    disabled=@disabled
-    onFileAdd=@onFileAdd
-  }}
+  {{this.bindListeners}}
 >
   {{yield
     (hash supported=this.supported active=this.active)