Add overdue invoices check (#31290)

- Rename current_user_account_too_young to account_too_young for
consistency
- Add has_overdue_invoices field to track billing status
- Block edit predictions when user has overdue invoices
- Add overdue invoice warning to inline completion menu

Release Notes:

- N/A

---------

Co-authored-by: Marshall Bowers <git@maxdeviant.com>

crates/zeta/src/zeta.rs

@@ -1578,8 +1578,9 @@ impl inline_completion::EditPredictionProvider for ZetaInlineCompletionProvider
             .zeta
             .read(cx)
             .user_store
-            .read(cx)
-            .current_user_account_too_young()
+            .read_with(cx, |user_store, _| {
+                user_store.account_too_young() || user_store.has_overdue_invoices()
+            })
         {
             return;
         }