Add "Thanks" for comments on Flow boards

bug: 61930
Change-Id: Id37a14e3c75c63419fc34e0b7c2e21f74b3fa875
Co-authored-by: Bencmq <bencmqwiki@gmail.com>
Add integration test for flowthank API

The test suite sets up various mocks for Flow classes and inserts
them into Flow\Container, so the API module retrieves the correct
mock classes instead.

Change-Id: I9c5e910e288f3dd72c66e68ca558265b8ca8ce5e