Eliminate mojo:resource_provider

services/catalog/manifest.json

 {
   "manifest_version":  1,
   "name": "mojo:catalog",
   "display_name": "Application Resolver",
   "capabilities": {
+    // Note, this section is provided for documentation only. Classes provided
+    // by this service must be stated in code in shell.cc as this manifest is
+    // not resolved until after several connections have been made.
+    "provided": {
+      "app": [ "filesystem::Directory" ]
+    },
     "required": {
-      "mojo:shell": { "classes": [ "shell:all_users" ] }      
+      "mojo:shell": { "classes": [ "shell:all_users", "shell:explicit_class" ] }
     }
   }
 }