Revert "Add hidden option to pxt.json to check if it hides extension from search."

This reverts commit 5e727a5.

This entry in the pxt.json file was added as a test.

Author: microbit-carlos

pxt.json

@@ -24,6 +24,5 @@
     "supportedTargets": [
         "microbit"
     ],
-    "preferredEditor": "blocksprj",
-    "hidden": true
+    "preferredEditor": "blocksprj"
 }