Change ResolverActivity base class to FragmentActivity

Change ResolverActivity's base class to FragmentMnager to make lifecycle
and view model related functionality available.

Only a few Activity's methods used by either ResolverActivity or
ChooserActivity are changed in the FragmentActivity hierarchy (except
for lifecycle methods e.g. onCreate):
 - setContentView: adds support for view lifecycle;
 - setEnterSharedElemenCallabck: adds support for older SDK
   versions, no-op in our case;
 - getFragmentManager(): deprecated by FragmetnActivity, switched over
   to getSupportFragmentManager().

Test: manual general functinality test, pinning
(ChooserTargetActionDialogFragment)
Test: atest IntentResolverUnitTests

Change-Id: If3b80c63facb9de04343409cf64db758700ec147
5 files changed