Split finalization scripts between vFRC and sFRC.

This splits out the AIDL/VNDK/sepolicy stuff from the SDK
finalization. However, in CI, we still do the vFRC step
as part of the first step.

We'll probably want to do some of the following:
- (maybe) add CI for the first step - a 'fina-0' branch
- add a way to do SDK finalizatoin without VINTF finalization
  because after VINTF finalization is submitted, people will
  develop in-progress interfaces that aren't done yet
- a lot of VINTF finalization is still not automated, so things
  like sepolicy and LL-NDK need to be added here.

Ignore-AOSP-First: b/304316873#comment10

Bug: 314010935
Test: N/A
Change-Id: I4831a14f5c5c3d757bd1d10a775d8cf4940d9a4a