This change ports the MenuButtonView UI element over to our new

TypeScript/spina framework.
The MenuButtonView had mostly replaced the old SplitButtonView,

which had been marked as deprecated since 4.0 (and which had become a

simple wrapper). As part of this change, I've moved the couple old uses

of SplitButtonView over to use MenuButtonView directly.

Verified "Publish" button functionality on the review dialog and draft

  review banner.
Ran js-tests.