Move api text files to android.txt/xml.

Mistake in aosp/661881 which migrated existing text files. Name the api file
for android.jar android.txt instead of N.txt, as described in the DD:
go/android-uses-libraries.

Also fix the Android.bp references.

Moves generated by:
$ for f in */*/api/*.xml; do mv "$f" "$(dirname $f)/android.xml"; done
$ for f in */*/api/*.txt; do mv "$f" "$(dirname $f)/android.txt"; done

Bug: 77525052
Test: These files are currently unused, but tested via make in follow-up CLs.
Change-Id: Ia4c88c0ce76400b5ede121d5b00b394d1fc4db5c
31 files changed