Move frameworks/base off the SRC_API_DIR variable.

This directory is going away. Migrate to the new paths, and replace the
long list of "since" arguments with a loop in the makefile. Also fix the
soong buildfile to use the new path and the 28 prebuilts.

This removes the need to update it every time an API is finalized (in make,
I don't know how to make loops in soong).

Bug: 77525052
Test: Verified variable is the same before & after, except for path change
Change-Id: I1d4e87e7840e979b83779a2aefe176e7c1ed1527
Merged-In: I1d4e87e7840e979b83779a2aefe176e7c1ed1527