Rewrite Icons from the TCS.

Because of the new app visibility constraints introduced in Android R,
apps may be unable to load icons from the TextClassifierService (TCS).
This is because the TCS returns "Icons" based on resources to the apps.
These resources were globally available until this new restriction.

In this CL, the TCMS rewrites responses with Icon(typ=RESOURCE) coming
from a TCS to responses with Icon(typ=URI). The new icons are backed
by a content provider that may be used to retrieve the necessary icons.

Bug: 151847511
Test: atest tests/tests/textclassifier/src/android/view/textclassifier/cts
Test: atest core/tests/coretests/src/android/view/textclassifier
Test: Select a phone number text, check that the "Call" icon shows
Change-Id: Ib63e54462508029cdf0e56c2c6a82ff4e81b02a8