Add autoproxy management commands

PluralKit.Core/Migrations/3.sql

@@ -6,8 +6,10 @@
 alter table system_guild add column autoproxy_mode int check (autoproxy_mode in (1, 2, 3, 4)) not null default 1;
 
 -- for member mode
-alter table system_guild add column autoproxy_member nullable references members (id) on delete set null;
+alter table system_guild add column autoproxy_member int references members (id) on delete set null;
 
 -- for latch mode
 -- not *really* nullable, null just means old (pre-schema-change) data.
-alter table messages add column guild bigint nullable default null;
+alter table messages add column guild bigint default null;
+
+update info set schema_version = 3;