add accessible view for comment thread widget

[meganrogge]

fixes #226091

[meganrogge]

@alexr00 I went down the rabbit hole trying to get the actions to work, but realized that once we have the ability to focus the comment that was focused in the accessible view on hide, that shouldn't be necessary.

Additionally, the actions in the comment thread toolbar are more conducive to be handled there vs the accessible view - such as reaction or edit comment (the accessible view is readonly by design).

[alexr00]

@meganrogge, I've enabled focusing on a specific comment with #228770. Just like before you need to call revealCommentThread and with this change the comment you pass in will get focus.

vscode/src/vs/workbench/contrib/comments/browser/commentsController.ts

Line 371 in fbdffe7

export function revealCommentThread(commentService: ICommentService, editorService: IEditorService, uriIdentityService: IUriIdentityService,

[alexr00]

@meganrogge, I know you want to get this merged and I didn't want to give you the run around by asking for more changes. I don't think setActiveCommentThread or the comments service is the best place to keep track of the "active comment for the accessible view", which is different from the "active comment which was last focused which we maintain for the purposes of extension API". I'd prefer to track "active comment for the accessible view" in the accessible view provider and remove this knowledge from the comment service, especially since this information doesn't seem to need to persist after the accessible view is closed. I've created a PR with these changes to merge into your own PR branch: #228866

[alexr00]

Thank you!