Include key maps based on file name

Rather than keeping a curated list where it's easy to miss things, just pick up
all of the possible key layouts, key character maps and input device configs in
framework/base/data/keyboards based on filename.

Change-Id: Iefa8eca491dcb6913e5b12bfda7096b6a5fedf18
(cherry picked from commit 9f5a6ee489f89c93491beef9bf64475fd2bfb0dd)