Caches don't necessarily work

[kawaii]

the API object caches guilds and channels but these don't necessarily work correctly

[Altreus]

We can use https://github.com/lizmat/ObjectCache on the ButReals.

Then we can use the new EVICT behaviour to force a re-fetch if necessary.

This will then just straight up cache everything. Nice.

[Altreus]

Put this back as enhancement because also I think it works OK now.