Easier banning of DC'd players.

[FunnyMan3595]

What Does This PR Do

Changes the ban process from Player Panel to rely on last_known_ckey instead of ckey, so that banning (including jobbanning) a disconnected player doesn't rely on manual bans.

Why It's Good For The Game

Better admin tooling is good.

Testing

Jobbanned myself from one of each category of ban.
Jobbanned myself from each ban category entire.
Banned myself. (It bailed out at the last second, but still kicked me.)
Banned a volunteer (thank you, Ratcliffe!) both while they were online and after they'd been kicked for the first ban.
Jobbanned the same volunteer after they were gone.

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Declaration

• I confirm that I either do not require pre-approval for this PR, or I have obtained such approval and have included a screenshot to demonstrate this below.

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Changelog

NPFC