feat: run all migrations in a transaction (#10966)

Updates coder/customers#365

This PR updates our migration framework to run all migrations in a single transaction. This is the same behavior we had in v1 and ensures that failed migrations don't bring the whole deployment down. If a migration fails now, it will automatically be rolled back to the previous version, allowing the deployment to continue functioning.

coderd/database/migrations/000058_template_acl.up.sql

@@ -1,5 +1,3 @@
-BEGIN;
-
 ALTER TABLE templates ADD COLUMN user_acl jsonb NOT NULL default '{}';
 ALTER TABLE templates ADD COLUMN group_acl jsonb NOT NULL default '{}';
 
@@ -44,5 +42,3 @@ SET
 		WHERE
 			templates.organization_id = organizations.id
 	);
-
-COMMIT;