docs: Updating TIF docs for new TIF Companion library.

The TIF Companion library makes creating a TIF app much easier, and
will be the recommended starting point for devs going forward. This
update adds docs on using this library, and modifies the existing
docs for creating a TIF app from scratch (for devs that can't use
the companion library).

Bug: 30678049
Change-Id: Iaa5a6d0a4c9f0f2faf1e30549aba754ced7cc27a