The Unified Review Banner: Review Menu is a follow-up to the Unified

Review Banner: Base Shell patch #10196.
The Review Menu will be registered on the unified banner and appear

when there is no current draft review. The menu will be displayed on

hover and will allow the user to either create a new, blank review,

or to mark it with "Ship It!". When there is a draft review, a discard

button will be registered on the unified banner to allow the user to

discard the current draft review.

Added new JS tests to test functionality added. All JS tests pass.
Note: there are some tests that will still be added to this patch in

ReviewablePageViewTests to test the changes introduced with the

Unified Review Banner: Review Menu in that file in this patch.