simpleperf: make app api available for profileable apps.

simpleperf: make app api available for profileable apps.

Add api-prepare cmd to prepare recording via app api.
Add api-collect cmd to collect recording data generated by app api. The
recording data is compressed into a zip file.
The two added cmds support both debuggable apps and profileable apps.
Move api_app_profiler.py to api_profiler.py. And use the two added cmds in it.

Also improve app_api code:
1. Fix finding simpleperf.
2. Use time based output filenames.

Bug: 123717243
Test: test manually, will add run python tests later.

Change-Id: I88c20578d01a84bc20ea72276f2cab0f3c4d9109