Clean-up usage of shared applyTransaction function

applyTransaction was doing too much which doesn't allow
for proper division of labor, has excessive indenting,
has double locking/binder-identity-management, and has
incorrect permissions messages. This CL just moves the
binder interface stuff and sync-engine management into
the actual binder interfaces.

Bug: 169035082
Test: builds/tests pass, no functional change
Change-Id: Iabd66ee51edb75c676a27033d834dab2d097d847