feat: ability to clear flyout blocks when language changes

src/engine/blocks.js

@@ -831,6 +831,14 @@ class Blocks {
         this.emitProjectChanged();
     }
 
+    /**
+     * Delete all blocks and their associated scripts.
+     */
+    deleteAllBlocks () {
+        const blockIds = Object.keys(this._blocks);
+        blockIds.forEach(blockId => this.deleteBlock(blockId));
+    }
+
     /**
      * Returns a map of all references to variables or lists from blocks
      * in this block container.