[FEATURE] - Snippet improvements

[rm-rf-tux]

• Make Tux send a welcome snippet automatically for new members.
• Add a permission system for snippets (especially their creation)

[Atmois]

Automatic welcome snippets are unliekly to be added but the second one is interesting, this could be incorpeated with #557

[FluxC0]

i want to extend this out to polls as well.

[rm-rf-tux]

We already have poll banning Should it just become poll perms then?