SDK / exoplayer

Remaining instrumentation tests either use android.os.Handler or rely on assets.
In the latter case, the tests are difficult to migrate due to differences
between the internal and external build systems, and configuration needed in
Android Studio. In addition, SimpleCacheSpanTest remains as an instrumentation
test because it fails due to a problem with string encoding on the internal
build (and two other tests in its package are kept with it because they depend
on it).

This test removes a dependency from testutils on Mockito, as a different
version of Mockito needs to be used for instrumentation tests vs Robolectric
tests, yet both sets of tests need to rely on testutils. Mockito setup is now
done directly in the tests that need it.

Move OggTestData to testutils so it can be used from both instrumentation and
Robolectric tests.

It may be possible to simplify assertions further using Truth but this is left
for possible later changes.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=167831435