cockpit.js: Put back cockpit.{resolve,reject}

Commit 132300e was premature, subscription-manager still uses
that [1]. Put it back, but in terms of the standard Promise API.

[1] candlepin/subscription-manager-cockpit#84

pkg/lib/cockpit.js

@@ -116,6 +116,14 @@ function factory() {
         },
     };
 
+    cockpit.resolve = function resolve(result) {
+        return Promise.resolve(result);
+    };
+
+    cockpit.reject = function reject(ex) {
+        return Promise.reject(ex);
+    };
+
     cockpit.defer = function() {
         return new Deferred();
     };