Update extensions to load when deserializing monitors. This is necessary when the monitor is the only part of the project that uses the extension. Update extension monitor color category.

src/engine/runtime.js

@@ -2102,9 +2102,9 @@ class Runtime extends EventEmitter {
         const block = categoryInfo.blocks.find(b => b.info.opcode === opcode);
         if (!block) return;
 
-        // TODO: should this use some other category? Also, we may want to format the label in a locale-specific way.
+        // TODO: we may want to format the label in a locale-specific way.
         return {
-            category: 'data',
+            category: 'extension', // This assumes that all extensions have the same monitor color.
             label: `${categoryInfo.name}: ${block.info.text}`
         };
     }