SF: Rename `postFramebuffer` for clarity

The "post" in "postFramebuffer" can be read as a preposition or a verb,
making the name less easy to understand. Furthermore, "framebuffer" is
typically used in the context of GPU composition, but this function
involves DPU composition.

Rename to "presentFrameAndReleaseLayers" to better describe what it
does. While we're at it, shorten "presentAndGetFrameFences" to simply
"presentFrame".

Splitting out from original motivating discussion in
Ib9d074671e32c95875ef7e0791dd95d6e595e47a.

Bug: 241285491
Bug: 259132483
Test: No new behavior; no new tests
Change-Id: I41df1d0b98c34eaffe44c5c29006356964c555a6