Ability to "Favorite" Proposals for Quick Access

Description: Add ability to "star" or "favorite" proposals for quick access from the dashboard and proposal list views.

Use Case/Example: As the pool of proposals increases, this feature would enable one-click access to frequently used proposals that a user such as a reviewer or auditor may not be directly assigned to. Such users may be accessing many proposals, so these favorited proposals may not be in the Recent Proposals queue, either.