Additions and strategy changes for LVK O4 run

[martinjohndyer]

The main purpose of this PR was to update the GW strategy and response for the O4 run (#70). After several iterations we decided on the following flow chart for event classification:

As well as this we have a new follow-up cadence for the majority of events, which reschedules pointings 1h after the initial observation at the same rank before falling below the others (see https://github.com/GOTO-OBS/gtecs-obs/pull/92).

Some other changes worth mentioning:

• Add the IGNORED strategy for notices.
• Add RAVEN external coincidence info if included in the notice, and use the combined map if provided (Dealing with coincident GW/GRB events #29).
• Add GWNotice.from_gracedb() to save the often slow IVORN downloads from 4pisky.
• Add specific channels for types of event (GW/GRB/NU) or ignored events, with the detailed messages posted to those channels while general messages stay in the default sentinel channel (and have the details linked using the permalink from Update Slack posting gtecs-common#7).
• Added a "WAKEUP" channel with a flag for specific strategies.
• Improve GRB waiting thread to add timeouts and not repeat for the same notice (GRB observing strategy: Fermi skymap overwrite #50 & https://github.com/GOTO-OBS/gtecs-control/pull/553).

[martinjohndyer]

I think this has been running for long enough to merge now. The wait was mostly to just check the retraction code worked, and it mostly did.