Add tests for input injection from various sources

Add tests that can be used to verify that input injection succeeds for
tests from the supported sources, which include Instrumentation and
UiAutomation.

These tests verify injection into a sparate test apk that has a
different uid than the tests. This also allows us to test that apps
that don't have the INJECT_EVENTS permission cannot inject events.

Bug: 229830384
Test: atest InputInjectionTest
Change-Id: Id60b552b5b6b10c83be1ef529e39f97c8a861e93
9 files changed