Fix problems with slimes, dionas and vox being nukies

[juliangiebel]

Description

The mentioned species all have issues with them that make them really bad for playing nuclear operatives as. As a result I implemented a generic antag whitelist for species and applied it to nukies excluding the problematic species in this PR: #29716. During the discussion we came up with the following list of suggestions for now:

General

• Warn players when they pick a species that is worse or more difficult to play

Diona

• Let them use magboots in some way

Slime

• Nerf or remove geras
• Start with n2 tank

Vox

• Should spawn with the harness on them, and start with N2 activated

This is also written down in a Discourse post