simpleperf: Use simpleperf_app_runner to profile profileable apps.

simpleperf: Use simpleperf_app_runner to profile profileable apps.

Simpleperf uses run-as to run in apps' context to profile debuggable
apps. In Android Q, we want to profile <profileable shell="true"> apps.
To support that, do below changes:
1. Add simpleperf_app_runner, which is similar to run-as, but is limited
to only run simpleperf commands in profileable apps.
2. Add code using simpleperf_app_runner inside simpleperf, so it doesn't
change current interface of using simpleperf.

Bug: 118835348
Test: run simpleperf manually.
Test: run simpleperf_unit_test.

Change-Id: I85a8e3c80fe0e3ccdee97de38be968cbccd1d263