implement recursive channel query

crates/collab/src/db/channel.rs

@@ -8,7 +8,6 @@ pub struct Model {
     pub id: ChannelId,
     pub name: String,
     pub room_id: Option<RoomId>,
-    // pub id_path: String,
 }
 
 impl ActiveModelBehavior for ActiveModel {}

crates/collab/src/db/channel_parent.rs

@@ -11,3 +11,6 @@ pub struct Model {
 }
 
 impl ActiveModelBehavior for ActiveModel {}
+
+#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
+pub enum Relation {}