[feature] Selective federation features

[tsmethurst]

Issue to group together + track issues that would be useful for allowing users + admins to limit certain types of federation with other instances, potentially disrupt spam.

• [ ] https://github.com/superseriousbusiness/gotosocial/issues/835
• [ ] https://github.com/superseriousbusiness/gotosocial/issues/1730
• [ ] https://github.com/superseriousbusiness/gotosocial/issues/9
• [ ] https://github.com/superseriousbusiness/gotosocial/issues/1800
• [x] https://github.com/superseriousbusiness/gotosocial/issues/2678
• [ ] https://github.com/superseriousbusiness/gotosocial/issues/2684

[NyaaaWhatsUpDoc]

have updated #9 and #835 as assigned to myself since i currently have nlnet funding allocated for them :)