[Twitch] Update remaining APIs to Helix

[Decicus]

More progress towards #22

Followage

• /followage/{channel}/{user} now uses Helix
• At the moment there's no caching for this endpoint, but I am debating on having a short cache shared with /followed/{channel}/{user}

Followers

1. /followers/{channel} now uses Helix
2. JSON responses have been removed (from what I know it was infrequently used anyways)
3. Parameters that have been removed and are no longer supported (mainly due to lack of support in Helix)
   • offset
   • cursor
   • direction
   • input (used alongside JSON responses)
   • username (see point 4)
4. Names listed are now always "display names" and not "Twitch usernames". Helix API does not include usernames and only display names.

Following

Same as the Followers changes, really - as they use the same endpoint.

Highlight / "Random Highlight"

Also updated to use Helix.
"Random highlight" has lost the ability to include the game name as Helix does not provide it. From what I know no one was using this functionality regardless.

TODO

• Update /following/{user} to use Helix as well
• Add caching to /twitch/followers - Might have to take count into consideration.

[Decicus]

Merged this for now to reduce how much the Kraken shutdown windows will affect DecAPI