SF: Rename postComposition and related for clarity

The "post" in "postComposition" (and related "onPostComposition") can be
read as a preposition or a verb, making the name less easy to understand.

We believe "postComposition" is intended to mean "after composition".
More precisely, it is called after calling `present`, so rename to
"onCompositionPresented". Rename the related "postComposition" on other
classes (Layer, Scheduler) to match.

Splitting out from original motivating discussion in
Ib9d074671e32c95875ef7e0791dd95d6e595e47a.

Bug: 241285491
Bug: 259132483
Test: No new behavior; no new tests

Change-Id: I7f62728ea35aee47ebeac10dc7de82258080690e
diff --git a/libs/gui/tests/Surface_test.cpp b/libs/gui/tests/Surface_test.cpp
index e7b1232..86ced2c 100644
--- a/libs/gui/tests/Surface_test.cpp
+++ b/libs/gui/tests/Surface_test.cpp
@@ -1341,7 +1341,7 @@
                 newFrame->mRefreshes[0].mGpuCompositionDone.mFenceTime :
                 FenceTime::NO_FENCE;
         // HWC2 releases the previous buffer after a new latch just before
-        // calling postComposition.
+        // calling onCompositionPresented.
         if (oldFrame != nullptr) {
             mCfeh->addRelease(nOldFrame, oldFrame->kDequeueReadyTime,
                     std::shared_ptr<FenceTime>(oldFrame->mRelease.mFenceTime));