Takes two parameters: Username, GroupTypes
Username: Same docs as CheckPW (confirm that properly docs the | option to specify table paths)
GroupTypes: List of GroupTypes to check, can be separated by any of $I, $CrLf, $Tab, or a comma.
If GroupTypes is set to a * it will return True for any valid user. If GroupTypes is blank or set to -* it will always return True, without validating the user.
Because IsGroupType does not consider if a user is currently logged in, it should never be used in place of SessionIsGroupType$. This function exists for the intended use case of API calls using API keys.