moderation: check bot hierarchy before performing kick/ban

[jo3-l]

Similar to https://github.com/jonas747/yagpdb/pull/887, but for kick and ban (totally forgot about this, otherwise I would've included it in the original PR 😄). This is a slightly more annoying/confusing issue for users - kick and ban would still send a moderation DM if the bot did not have sufficient permissions to moderate the user. Works fine on selfhost, as far as I can see.

[jogramming]

this has conflicts now

[jo3-l]

Should be fixed now @jonas747

[jogramming]

Not needed after https://github.com/jonas747/yagpdb/commit/1772fe30bcd4a3849781e3ee92cb54b75f78e433

[jo3-l]

Actually, not sure if https://github.com/jonas747/yagpdb/commit/1772fe30bcd4a3849781e3ee92cb54b75f78e433 fully resolves this -- as far as I can see the issue will still occur if the target member is higher than the bot. WDYT @jonas747? Happy to modify this PR to just add that fix / keep it closed if you don't think it's worth the additional complexity 😄

[jogramming]

I'll reopen, but we only need that one check then

[jo3-l]

Should be good now, just tested.