Test: Comment API contributions

[RMacfarlane]

Refs: #68020

• any @isidorn MacOS
• any @dbaeumer

Authors: @rebornix, @RMacfarlane

Complexity: 4

This month, we finalized the new commenting API. Much of this has already been tested and vetted, the change from last month was to support menu contributions to:

• comments/commentThread/title
• comments/commentThread/actions
• comments/comment/title
• comments/comment/actions

The two "actions" contribution points should render the commands as buttons below the comment text area, at the comment or thread level. We also added these new context keys:

• commentController, similar to scmProvider, can be used to match the id of a comment controller
• commentIsEmpty, when the comment text area has no input
• commentThreadIsEmpty, when the comment thread has no comments
• comment, which is used to check the contextValue of Comment
• commentThread, which is used to check the contextValue of CommentThread

Please test that you can contribute commands to these areas, and control when they are shown and enabled with the context keys. Comment API sample for reference: https://github.com/microsoft/vscode-extension-samples/tree/048fa2f156090c43cbe56bc4e2788aa77c091a5d/comment-sample