API feedback: Translation View API improvement.

1. Rename dispatchRequestTranslation().
2. Provide what should be done in onViewTranslationResponse().

Bug: 186578468
Bug: 186578311
Test: atest CtsTranslationTestCases
Test: manual.
CTS-Coverage-Bug: 177960696

Change-Id: Id90e7d68a92ec17ec302d7ff05ef67c8bfa6454b