Rename "groups" => "groupsService" where possible

The name of the "groups" service is slightly ambiguous in this context.
We can't rename the prop because service dependencies are resolved by
name and the service is called "groups" when registered with Angular.

src/sidebar/components/group-list-item.js

@@ -16,7 +16,7 @@ const MenuItem = require('./menu-item');
  * The item has a primary action which selects the group, along with a set of
  * secondary actions accessible via a toggle menu.
  */
-function GroupListItem({ analytics, group, groups }) {
+function GroupListItem({ analytics, group, groups: groupsService }) {
   const canLeaveGroup = group.type === 'private';
   const activityUrl = group.links.html;
   const hasActionMenu = activityUrl || canLeaveGroup;
@@ -43,7 +43,7 @@ function GroupListItem({ analytics, group, groups }) {
     const message = `Are you sure you want to leave the group "${group.name}"?`;
     if (window.confirm(message)) {
       analytics.track(analytics.events.GROUP_LEAVE);
-      groups.leave(group.id);
+      groupsService.leave(group.id);
     }
   };
 
@@ -111,6 +111,7 @@ function GroupListItem({ analytics, group, groups }) {
 GroupListItem.propTypes = {
   group: propTypes.object.isRequired,
 
+  // Injected services.
   analytics: propTypes.object.isRequired,
   groups: propTypes.object.isRequired,
 };

src/sidebar/components/test/group-list-item-test.js

@@ -9,7 +9,7 @@ const { events } = require('../../services/analytics');
 
 describe('GroupListItem', () => {
   let fakeAnalytics;
-  let fakeGroups;
+  let fakeGroupsService;
   let fakeStore;
   let fakeGroupListItemCommon;
 
@@ -41,7 +41,7 @@ describe('GroupListItem', () => {
       orgName: sinon.stub(),
     };
 
-    fakeGroups = {
+    fakeGroupsService = {
       leave: sinon.stub(),
     };
 
@@ -59,7 +59,7 @@ describe('GroupListItem', () => {
     return mount(
       <GroupListItem
         group={fakeGroup}
-        groups={fakeGroups}
+        groups={fakeGroupsService}
         analytics={fakeAnalytics}
       />
     );