feat: include member count in get_workspace API (#6747)

* feat: add member count for workspace

* fix: sqlite migration

frontend/rust-lib/flowy-sqlite/src/schema.rs

@@ -101,6 +101,7 @@ diesel::table! {
         created_at -> BigInt,
         database_storage_id -> Text,
         icon -> Text,
+        member_count -> BigInt,
     }
 }