Work items discussions: Emoji reactions

Acceptance Criteria

MVC 1:

• Add an award emoji
• Remove an award emoji
• Display details of users who added a particular award emoji
• Adding an emoji to a comment clears open todos on the work item.

MVC 2:

• Within the award emoji picker, integrate custom emojis into the picker.

Implementation notes

• I think the emoji picker may need to be refactored based on previous conversations that happened with the folks working on custom emojis.

Availability and Testing

Ensure updated test coverage in unit/integration/feature tests.