Add `dev.fe-helpers` to expose the current query to CLJS REPLs (#34997)

Use `(dev.fe-helpers/current-query)` from a CLJS REPL to get the query currently open in the UI.

dev/src/dev/fe_helpers.cljs

+(ns dev.fe-helpers)
+
+(defn redux-state []
+  (let [root  (js/document.querySelector "#root")
+        store (.. root -_reactRootContainer -_internalRoot -current -child -memoizedProps -store)]
+    (.getState store)))
+
+(defn current-card []
+  (.. (redux-state) -qb -card))
+
+(defn current-legacy-query-js []
+  (.-dataset_query (current-card)))
+
+(defn current-query []
+  (.-__MLv2_query js/window))

frontend/src/metabase-lib/Question.ts

@@ -1221,6 +1221,12 @@ class Question {
       );
     }
 
+    // Helpers for working with the current query from CLJS REPLs.
+    if (process.env.NODE_ENV === "development") {
+      window.__MLv2_metadata = metadata;
+      window.__MLv2_query = this.__mlv2Query;
+    }
+
     return this.__mlv2Query;
   }