fs_config: generate oem AID header file

Generate an OEM AID_<name> header file seperate from fs_config
header file and provide details on how to export this interface
into native code.

Test: That ls, ps, chown and services function for built in
services as before.
Change-Id: Ie8ce6585e0721b52633ee50d62dcfe796e178f65
Signed-off-by: William Roberts <william.c.roberts@intel.com>