Making TextClassifier helper objects parcelable

- EntityConfidence is no longer generic because it doesn't mix well with
  being Parcelable.
- Deprecated OnClick listeners in TextClassification as they can't be
  parceled. (Outright removed the secondary listeners that were not part
  of any release)
- Classes that were present in previous releases have their parceling
  factored out into ParcelableWrapper helper classes for backwards
  compatibility.

Bug: 67609167
Test: Added
Change-Id: I820ca4abc6b80f90007ab4424bc5df2a14f797b0