refactor: migrate to typeorm 3.0 (#8443)

* wip

* wip

* wip

* Update following.ts

* wip

* wip

* wip

* Update resolve-user.ts

* maxQueryExecutionTime

* wip

* wip

packages/backend/src/server/api/endpoints/username/available.ts

@@ -1,5 +1,6 @@
 import define from '../../define.js';
 import { Users, UsedUsernames } from '@/models/index.js';
+import { IsNull } from 'typeorm';
 
 export const meta = {
 	tags: ['users'],
@@ -29,12 +30,12 @@ export const paramDef = {
 // eslint-disable-next-line import/no-default-export
 export default define(meta, paramDef, async (ps) => {
 	// Get exist
-	const exist = await Users.count({
-		host: null,
+	const exist = await Users.countBy({
+		host: IsNull(),
 		usernameLower: ps.username.toLowerCase(),
 	});
 
-	const exist2 = await UsedUsernames.count({ username: ps.username.toLowerCase() });
+	const exist2 = await UsedUsernames.countBy({ username: ps.username.toLowerCase() });
 
 	return {
 		available: exist === 0 && exist2 === 0,