Add getConfig() method to plugin restApi interface

The REST API interface of Gerrit core's UI has a method to retrieve the
server config and to cache it. This method was not enabled in the
REST API interface for plugins. However, to e.g. find out which
account fields are editable it would be helpful to have access to the
cached server config.

Change-Id: Ida161f8adca075f6470b361290ba091d99e3996d

polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-rest-api.js

diff --git a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-rest-api.js b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-rest-api.js
index eb0c7e0..10deb95 100644
--- a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-rest-api.js
+++ b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-rest-api.js
@@ -38,6 +38,10 @@
     return getRestApi().getVersion();
   };
 
+  GrPluginRestApi.prototype.getConfig = function() {
+    return getRestApi().getConfig();
+  };
+
   GrPluginRestApi.prototype.invalidateReposCache = function() {
     getRestApi().invalidateReposCache();
   };

polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-rest-api_test.html

diff --git a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-rest-api_test.html b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-rest-api_test.html
index 5983621..7a59337 100644
--- a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-rest-api_test.html
+++ b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-rest-api_test.html
@@ -42,6 +42,7 @@
         send: sendStub,
         getLoggedIn: sandbox.stub(),
         getVersion: sandbox.stub(),
+        getConfig: sandbox.stub(),
       };
       stub('gr-rest-api-interface', Object.keys(restApiStub).reduce((a, k) => {
         a[k] = (...args) => restApiStub[k](...args);
@@ -133,12 +134,20 @@
       });
     });
 
-    test('getConfig', () => {
+    test('getVersion', () => {
       restApiStub.getVersion.returns(Promise.resolve('foo bar'));
       return instance.getVersion().then(result => {
         assert.isTrue(restApiStub.getVersion.calledOnce);
         assert.equal(result, 'foo bar');
       });
     });
+
+    test('getConfig', () => {
+      restApiStub.getConfig.returns(Promise.resolve('foo bar'));
+      return instance.getConfig().then(result => {
+        assert.isTrue(restApiStub.getConfig.calledOnce);
+        assert.equal(result, 'foo bar');
+      });
+    });
   });
 </script>