Merge changes from topic 'fsconfig-2'
* changes:
fs_config: add unit tests
fs_config: drop fs_config_files/dirs PRODUCT_PACKAGES requirement
fs_config: add group to build
fs_config: introduce group generator
fs_config: add passwd to build
fs_config: introduce passwd generator
fs_config: generate friendly in AID class
fs_config: limit characters for AID_<name> sections
fs_config: generate oem AID header file
fs_config: android_id header generator
fs_config: support parsing android_filesystem_config.h
fs_config: modularize fs_config_generator