Split the FaceIface class in three parts

1) FaceTags in libs/database/faces: Contains utility code to find or create face tags
   with TagsCache help
2) FaceTagsEditor: Code to add, remove or confirm face entries in the database.
   Strictly only database dependency, no libkface
DatabaseFace is moved to libs/database/faces as well
3) FaceIface: Code to detect and recognize with libkface, and merge the results.
   Inherits FaceTagsEditor and reimplements the methods for normal tags
   using MetadataManager

CCBUG: 271030