Make framework classes non final

These classes are being made extensible (open) so that we can
extend these classes in the corresponding jetack classes. If we don't
extend these classes, we will end up with duplicate classes
in the framework & Jetpack, which will cause confusion
for the developers. The jetpack classes have the same purpose, excet tha
they will have strucutred fields as opposed to generic bundles/slices.

Test: make
Bug: 253155222
API-Coverage-Bug: 247549381

Change-Id: Id257ced662dd98fcee9e1396bb6a72709d5d160d