[framework] Prepare profile for app code paths

This CL is an intermediate step to enable the use of profiles shipped in
the dex metadata files.

The preparation consist of:
- creating the current profile
- merging the profile from the dex metadata file (if present) into the
reference profile

and happens:
- after the application data directory is created, to capture system
apps.
- post-install (right before we dexopt), to capture any new code paths

Test: manual (install apps and splits, take OTA)
Bug: 30934496

Change-Id: Id36474ab629ad3ffafd24381d30e3d88ac02d576