Work Item: View description diff

Problem

Legacy issue detail view allows you to view the diff for the description when it is changed.

Proposal

MVC 1

Fast follow the legacy issue experience by expanding/collapsing diffs within the activity feed.

Collapsed	Expanded

Moved Post MVC to #406370

1. Provide a UI mechanism to view the description diff in line with the primary description area. [1]
   • Potential challenge: If we show the diffs within the description, will there be conflicts depending on which type of editor is currently selected? Does it matter? [1]:
2. Provide a diffs viewer, separate from the editor, with all revisions and ability to restore previous versions
3. Provide a "Comments" filter, with shortcuts from edited note

Acceptance

• When the description on a work item is updated, I can view the diff to see what was changed.
• I can efficiently find and review all changes to the description over time.
• I can delete a diff to avoid accidentally leaking confidential or sensitive data.