collab: Adapt rate limits based on plan (#15548)

This PR updates the rate limits to adapt based on the user's current
plan.

For the free plan rate limits I just took one-tenth of the existing rate
limits (which are now the Pro limits). We can adjust, as needed.

Release Notes:

- N/A

---------

Co-authored-by: Max <max@zed.dev>

crates/collab/src/db/queries/billing_subscriptions.rs

@@ -110,13 +110,15 @@ impl Database {
         .await
     }
 
-    /// Returns all of the active billing subscriptions for the user with the specified ID.
-    pub async fn get_active_billing_subscriptions(
-        &self,
-        user_id: UserId,
-    ) -> Result<Vec<billing_subscription::Model>> {
+    /// Returns whether the user has an active billing subscription.
+    pub async fn has_active_billing_subscription(&self, user_id: UserId) -> Result<bool> {
+        Ok(self.count_active_billing_subscriptions(user_id).await? > 0)
+    }
+
+    /// Returns the count of the active billing subscriptions for the user with the specified ID.
+    pub async fn count_active_billing_subscriptions(&self, user_id: UserId) -> Result<usize> {
         self.transaction(|tx| async move {
-            let subscriptions = billing_subscription::Entity::find()
+            let count = billing_subscription::Entity::find()
                 .inner_join(billing_customer::Entity)
                 .filter(
                     billing_customer::Column::UserId.eq(user_id).and(
@@ -124,11 +126,10 @@ impl Database {
                             .eq(StripeSubscriptionStatus::Active),
                     ),
                 )
-                .order_by_asc(billing_subscription::Column::Id)
-                .all(&*tx)
+                .count(&*tx)
                 .await?;
 
-            Ok(subscriptions)
+            Ok(count as usize)
         })
         .await
     }