Use Guice to feed dependencies to ApprovalsUtil

Classes shouldn't use static methods with long dependency lists. They
should use Guice injection to get their dependencies, especially if
they are very common ones like ReviewDb or ApprovalTypes.

ChangeUtil is a disaster so just paper over the one call site that is
harder to clean up.

Change-Id: Ia32fbf32175dcc84f8ae78361b128ce527ea99fa
5 files changed