Add streaming service Hulu

[Manitary]

Add hulu.py, working as similarly as possible to other existing services (CR/HIDIVE), I figured this could be needed as we have an exclusive series this season and it may happen again in the future.
(Technically it's also on D+, but I have no idea how to get data from that one)

Include some explanation of how the relevant data is scraped from the show's page, as well as two examples from Heavenly Delusions and Attack on Titan.

Two things observed based on the two series:

• Episode times may be inaccurate: Heavenly Delusions releases at 1pm UTC (according to livechart.me and some Reddit comments) while its webpage lists it at 12pm UTC. Regardless of whether this is information is correct, there is a dictionary series name -> timedelta put in place for such instances, defaulted to 0.
• Episode numbering between seasons may be wonky. An appropriate remote_offset probably takes care of it well enough, combined with the release date filtering out previous seasons.

NOTES:

• After adding this file, the setup command needs to be run in order to add Hulu to the Services table.
• In the seasonal configuation files, hulu|Hulu should be replaced with hulu, otherwise the link will be added to the LiteStreams table, and two links to the same stream will be created in the post body.
• Likewise, if the edit command is run to add currently airing series, a new entry in the Streams table will be created, and existing entries in the LiteStreams table should be removed manually.