[ravenwood] Handle asserts on looper threads gracefully

Assertion failures on the main thread is *usually* recoverable.
So let's catch them without killing the looper, report them as
test failures, but continue running.

Without it, the "recoverable exception" check in RREC is actually
broken because even if we catch the exceptions, the looper would still
quit.

Fix: 417275682
Test: $ANDROID_BUILD_TOP/frameworks/base/ravenwood/scripts/run-ravenwood-tests.sh -s
Flag: EXEMPT host test change only
Change-Id: I2b5af4a847889bd6570fc8146d65bd9383428373