Processor for @UnsupportedAppUsage annotations.

The processor outputs unsupportedappusage_index.csv, containing source
position info for every@UnsupportedAppUsage annotation processed. It is a
mapping of dex signature to the source postion of the annotation on that
signature. It is used as input for scripts which update the annotations.

We include a META-INF file which causes the compiler to automatically
pick up the annotation processor. Otherwise we would need to explicitly
specify the processor with a -processor flag to javac.

We create a new build target for just the @UnsupportedAppUsage annotation
and the @IntDef annotation (which it depends on) so that the processor can
also depend on that directly.

The processor only runs on a new build target framework-annotation-proc
so that it is not invoked as part of a regular build. This is done so
that we don't slow down peoples builds: Soong does not support annotation
processors when javac sharding is in use. This workaround can be removed
once b/77284273 is fixed.

Test: m framework-annotation-proc
Bug: 113853502

Change-Id: Ie9cd5a90ddf7a51f6035e849703fc39ad9127557