Fix compatchanges.html doc generation

Add support for compat changes that have the @EnabledSince annotation,
and treat the deprecated @EnabledAfter(X) annotations as
@EnabledSince(X+1) when generating docs.

Bug: 172238506
Test: m offline-sdk-docs
Change-Id: Iab10c1b47aa3c78fae80ddc8ff95815511643217
2 files changed