Muted Role is not applied to forums

At present, `>>setup muterole` does not apply any permissions to Forum Channels for the Muted role (when it really should do so, turning off Create Posts, Send Messages In Posts, and Add Reactions).

Start at the `>>setup muterole` command and trace how the Muted role permissions are applied to channels. Check the Forum Channel permission handling for Create Posts, Send Messages In Posts, and Add Reactions; done means those permissions are disabled for the Muted role in forums.

Written by the indexing model from the issue text.