Ensure UWB conforms to API guidelines

Adds the necessarily @NonNull and @hide annotations to the UWB classes
to be in alignment with API guidelines. Also ensures that getters and
setters for the same values have consistent names.

Bug: 170323306
Test: atest UwbManagerTests

Change-Id: I26ce17c9ef1eaa63261d83fa341451e04b164970
10 files changed