Change TextClassification to use RemoteActions

Behavioural changes:
- Every action now as an icon, and instead hints via RemoteAction whether
  the icon should be shown or not.
- Icons are now taken from the app default, not the activity.
  (That way, we can construct a lightweight resource backed Icon)
- Legacy intents are no longer parceled for security reasons.
  (TextClassificatio wasn't parcelable in O)
- TextClassifications built with the new API will always return null for
  getIntent, but provide a getOnClickListener.
- Accessibility descriptions are now provided for action mode items.

Testing changes:
- Removed URI checks from TCM test because PendingIntent hides this info.

Bug: 73950205
Test: atest FrameworksCoreTests:TextClassificationManagerTest
Test: atest FrameworksCoreTests:TextClassificationTest
Test: atest CtsViewTestCases:TextClassificationManagerTest
Test: atest CtsViewTestCases:TextClassifierValueObjectsTest
Test: atest CtsWidgetTestCases:TextViewTest
Test: atest CtsWidgetTestCases:EditTextTest
Change-Id: I6706d2c342a8bbb9de0146a48c8b8aac9d9c7d83