Add Confluent logo as webview icon

[noeldevelops]

Summary of Changes

• A confluent logo as the webview "favicon" in the tabs we generate.

Any additional details or context that should be provided?

Light theme	Dark theme

Pull request checklist

Please check if your PR fulfills the following (if applicable):

Tests

• Added new
• Updated existing
• Deleted existing

Other

• All new disposables (event listeners, views, channels, etc.) collected as for eventual cleanup?

• Does anything in this PR need to be mentioned in the user-facing CHANGELOG or README?
• Have you validated this change locally by packaging and installing the extension .vsix file?

  gulp clicktest

[confluent-cla-assistant]

🎉 All Contributor License Agreements have been signed. Ready to merge.
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[shouples]

Quick mention that we also have https://github.com/confluentinc/vscode/blob/main/resources/icons/logo.svg used for the custom ThemeIcons, but maybe we need some general icon cleanup. 🤔

[noeldevelops]

Quick mention that we also have https://github.com/confluentinc/vscode/blob/main/resources/icons/logo.svg used for the custom ThemeIcons, but maybe we need some general icon cleanup

@shouples agreed maybe a little icon cleanup is in order?
In the case of the one you linked, its currentcolor fill won't work since this icon ends up being used like an image file, so I had to make sure we had a pre-colored light & dark one. Webview also won't take a ThemeIcon type here which is unfortunate.

[shouples]

💯