simpleperf: add --only-host-test option in do_test.py.

Add option to only run host tests, which are much faster
than running all tests.

Also import Iterator from typing to run on python3.8.

Bug: 185526771
Test: run scripts/test/test.py --only-host-test.

Change-Id: Idd7225eb21cc48f6e5db100d387227c33e0b8039
3 files changed