Use etag to cache youtube responses

[dotted]

This should drastically reduce quota usage for youtube api.

Questions:

• Should the old cache logic be removed?
• Should we dump the this.etags into the DB to persists the etags further reducing quota cost?

Todo:

• Fix tests

[johnpyp]

Since the bot is generally long-running for 24h+ I doubt it's worth it to dump etags into the db, unless we're still running into api quota issues after this change.

Other than deleting a stale comment, LGTM

[shadedred]

This should hopefully provide better caching, sufficient enough to keep us under the quota. The next solution here, should this still hit the quota, is to not us the search API, and get destiny to generate an authenticated key on his account itself that can use the https://developers.google.com/youtube/v3/live/docs/liveBroadcasts/list list (my broadcasts) endpoint, eliminating the search call, which is about 160 times more expensive than every other call in terms of quota.

[dotted]

Pretty sure dumping this.etags into the DB and loading it on startup is much less involved than trying to get Destiny to get us that key. 🤣

[shadedred]

I agree 😆 but lets give this a shot and see how the quotas fair tomorrow