simpleperf: keep generated data of test.py.

Keep generated data of each test of test.py in a separate directory,
so we can:
1) check generated html after testing.
2) check profiling data for failed tests.
3) run tests for different devices in different dirs at the same time.

Also continue test when a test pass fails in run_tests().

Bug: 142972498
Test: run test.py.

Change-Id: If8468f0e180d441b74c070b978375b27c293a006
2 files changed