[Coins] Consider making some/all of the Coins module PM-only

[fndax]

The commands in the Coins module are extremely spammy and half the time people don't realize that they work just fine in PM. I could probably make a good argument for just deleting coins.py altogether, but since i do not "hate fun" I suggest some or all of its commands should have @utils.kwarg("private_only", True) added instead.

If you want suggestions on specific commands to make PM-only because doing them all is "too much" or something, I suggest redeemcoins, flip, and roulette, since those seem to be the spammiest ones.

(This issue is heavily opinion-based and I'm fine if you disagree and close it.)

[jesopo]

might make it a setting, to turn it off in channels that like to spam coin stuff

[examknow]

Personally, I think it would be a lot more useful to just allow channels to disable (not just filter) any commands they want on a per-channel basis