Split "@everyone" into "@Guest" and "@Member"

[at]Guest

Users who have joined a server that has the "Membership Screening" featured enabled but has yet to acknowledge/accept the terms shown.

[at]Member

Users who have accepted the terms shown on the "Membership Screening" panel, or for servers that do not have the feature nor have "Community Features" enabled.

(Both roles should be allowed to have a colour applied. i.e. black for Guest and default for members.)