[MM-16910] Set footerColor the same as navBarBackgroundColor (#3002)

* Set footerColor the same as navBarBackgroundColor

* Oops, forgot __snapshots__

app/components/sidebars/main/__snapshots__/main_sidebar.test.js.snap

@@ -0,0 +1,13 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`ChannelSidebar should match, full snapshot 1`] = `
+<DrawerLayout
+  drawerPosition="left"
+  drawerWidth={-30}
+  isTablet={false}
+  onDrawerClose={[Function]}
+  onDrawerOpen={[Function]}
+  renderNavigationView={[Function]}
+  useNativeAnimations={true}
+/>
+`;

app/components/sidebars/main/main_sidebar.js

@@ -378,7 +378,7 @@ export default class ChannelSidebar extends Component {
             <SafeAreaView
                 navBarBackgroundColor={theme.sidebarBg}
                 backgroundColor={theme.sidebarHeaderBg}
-                footerColor={theme.sidebarHeaderBg}
+                footerColor={theme.sidebarBg}
             >
                 <DrawerSwiper
                     ref={this.drawerSwiperRef}

app/components/sidebars/main/main_sidebar.test.js

@@ -0,0 +1,38 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+import React from 'react';
+import {shallow} from 'enzyme';
+
+import Preferences from 'mattermost-redux/constants/preferences';
+
+import ChannelSidebar from './main_sidebar';
+
+jest.mock('react-intl');
+
+describe('ChannelSidebar', () => {
+    const baseProps = {
+        actions: {
+            getTeams: jest.fn(),
+            logChannelSwitch: jest.fn(),
+            makeDirectChannel: jest.fn(),
+            setChannelDisplayName: jest.fn(),
+            setChannelLoading: jest.fn(),
+        },
+        blurPostTextBox: jest.fn(),
+        currentTeamId: 'current-team-id',
+        currentUserId: 'current-user-id',
+        deviceWidth: 10,
+        isLandscape: false,
+        teamsCount: 2,
+        theme: Preferences.THEMES.default,
+    };
+
+    test('should match, full snapshot', () => {
+        const wrapper = shallow(
+            <ChannelSidebar {...baseProps}/>
+        );
+
+        expect(wrapper.getElement()).toMatchSnapshot();
+    });
+});