(This commit also modifies UI)
Instead of pinging Twitch every time the program starts up, only pings
for new servers when the ingests are actually being used, and when the
UI uses the auto-configuration dialog.
If ingests have not been cached when using the "Auto" server, it will
wait for 3 seconds max to query the Twitch ingest API. If it takes
longer than 3 seconds or fails, it will defer to SF. If ingests were
already cached, then it will use the existing cache immediately.
Updates ingests via Twitch's ingest API. The servers are ordered by
closest to farthest from the user via the API. It's probably still good
to keep the services.json Twitch ingests updated in case there are
issues with the Twitch ingest API, but otherwise the ingests will update
from Twitch itself every time the program is opened automatically.
jp9000