collab: Setup database for LLM service (#15882)

This PR puts the initial infrastructure for the LLM service's database
in place.

The LLM service will be using a separate Postgres database, with its own
set of migrations.

Currently we only connect to the database in development, as we don't
yet have the database setup for the staging/production environments.

Release Notes:

- N/A

crates/collab/src/db/tests.rs

@@ -11,6 +11,8 @@ mod feature_flag_tests;
 mod message_tests;
 mod processed_stripe_event_tests;
 
+use crate::migrations::run_database_migrations;
+
 use super::*;
 use gpui::BackgroundExecutor;
 use parking_lot::Mutex;
@@ -91,7 +93,9 @@ impl TestDb {
                 .await
                 .unwrap();
             let migrations_path = concat!(env!("CARGO_MANIFEST_DIR"), "/migrations");
-            db.migrate(Path::new(migrations_path), false).await.unwrap();
+            run_database_migrations(db.options(), migrations_path, false)
+                .await
+                .unwrap();
             db.initialize_notification_kinds().await.unwrap();
             db
         });