Allow !ban, !vban, and !pban to take a duration

[Shivansh-007]

Closes #1563
Closes #1566

Apply temporary ban if duration is specified while banning a user.

Screenshots

Applying a ban with duration

Proof in #all-logs

[ToxicKidz]

[mbaruh]

It looks good in the context of the issue, though it creates inconsistency with pban and vban

[Xithrius]

To make this consistent with other commands, please make purgeban not take any argument for purge days, but instead take only ban days. If time exists, don't permaban.

Please also do the same thing for voiceban, where if a time is supplied, it won't be permanent.

Full explanation: #1566.

[mbaruh]

You're still going over the character limit for commit titles :)
Keep them concise. Any details of context or reasoning can go into the body.

Also not sure why you're prepending the (infractions) part.

[mbaruh]

This can be an opportunity to add some more related tests, but you don't have to.

[Xithrius]

Looks very well to me.

[Shivansh-007]

This can be an opportunity to add some more related tests, but you don't have to.

Tests for the new feature I added in this PR, or the complete pban and ban command?

[mbaruh]

For what you added.

[Shivansh-007]

For what you added.

Alright, I will do that.