IJB-A database implemented incorrectly

The IJB-A database interface is not implemented correctly, and it is not tested -- the tests are skipped with an error message (see e.g. https://gitlab.idiap.ch/bob/bob.bio.face/builds/26262):

bob.bio.face.test.test_databases.test_ijba ... SKIP: Skipping test since the database bob.db.ijba seems not to be available: The given command line option 'ijba' is neither a resource for a 'database', nor an existing configuration file, nor could be interpreted as a command (error: name 'ijba' is not defined)

IJB-A needs to implement the BioFileSet protocol, but in its current version, this is not done. Also, for IJB-A we do not have all annotations for all images, so the test here: https://gitlab.idiap.ch/bob/bob.bio.face/blob/master/bob/bio/face/test/test_databases.py#L123 will most probably fail.

Also, we have the same issue for the annotations as mentioned in #14 (closed) and bob#235 (closed).

I can provide an implementation for the database, making sure that all the issues are solved. We might need to change the implementation of the annotations, when we have come up with a generic solution for #14 (closed).