Revise InterfaceRegistry API to support filtering interfaces @ Bind() time.

services/catalog/manifest.json

 {
   "name": "service:catalog",
   "display_name": "Application Resolver",
   "interface_provider_specs": {
     // NOTE: This manifest is for documentation purposes only. Relevant
     // capability spec is defined inline in the ServiceManager implementation.
     //
     // TODO(rockot): Fix this. We can bake this file into ServiceManager at
     // build time or something. Same with service:service_manager.
     "service_manager:connector": {
       "provides": {
         "app": [ "filesystem::mojom::Directory" ],
         "control": [ "catalog::mojom::CatalogControl" ]
       },
       "requires": {
-        "service:service_manager": [
-          "service_manager:all_users",
-          "service_manager:explicit_class"
-        ]
+        "service:service_manager": [ "service_manager:all_users" ]
       }
     }
   }
 }