improved library scan speeds, added library manager component

-libraries tab now opens a library manager
-choose library directory, manually soft scan and rescan
-batched db queues
-mp3 header-based duration extraction

backend/database/sql/sqlcgen/release_groups.sql.go

@@ -68,6 +68,15 @@ func (q *Queries) CreateReleaseGroupFull(ctx context.Context, arg CreateReleaseG
 	return i, err
 }
 
+const deleteAllReleaseGroups = `-- name: DeleteAllReleaseGroups :exec
+DELETE FROM release_groups
+`
+
+func (q *Queries) DeleteAllReleaseGroups(ctx context.Context) error {
+	_, err := q.db.ExecContext(ctx, deleteAllReleaseGroups)
+	return err
+}
+
 const deleteReleaseGroup = `-- name: DeleteReleaseGroup :exec
 DELETE FROM release_groups 
 WHERE id = ?