feat(backend): add DELETE /users/@me endpoint

scripts/migrate/005_delete_users.sql

@@ -0,0 +1,10 @@
+-- +migrate Up
+
+-- 2023-03-07: add delete functionality
+
+-- if not null, the user is soft deleted
+alter table users add column deleted_at timestamptz;
+-- if true, the user deleted their account themselves + should have option to reactivate; should also be deleted after 30 days
+alter table users add column self_delete boolean;
+-- delete reason if the user was deleted by a moderator
+alter table users add column delete_reason text;