feat: add Gene Normalizer sources

[jsstevenson]

• I split up the NCBI stuff because I think that while gene info/history are sort of tightly coupled (ideally they should be the same version), they're qualitatively different, and not dependent on, the genome annotation file.
• We get all this stuff via FTP. It's a lot harder to mock (I didn't bother here -- we weren't previously mocking it in Gene Normalizer tests) and also the EBI FTP server seems to just block login attempts sometimes... might be worth it to just switch to HTTP.