PLT-6445 Migrate add_command.jsx to be pure and use Redux (#6804)

* Migrate add_command.jsx to be pure and use redux

* Add basic test for AddCommand component

webapp/tests/components/integrations/add_command.test.jsx

@@ -0,0 +1,30 @@
+// Copyright (c) 2017-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+import React from 'react';
+import {shallow} from 'enzyme';
+
+import * as Utils from 'utils/utils.jsx';
+import AddCommand from 'components/integrations/components/add_command/add_command.jsx';
+
+describe('components/integrations/AddCommand', () => {
+    test('should match snapshot', () => {
+        function emptyFunction() {} //eslint-disable-line no-empty-function
+        const teamId = Utils.generateId();
+
+        const wrapper = shallow(
+            <AddCommand
+                team={{
+                    id: teamId,
+                    name: 'test'
+                }}
+                addCommandRequest={{
+                    status: 'not_started',
+                    error: null
+                }}
+                actions={{addCommand: emptyFunction}}
+            />
+        );
+        expect(wrapper).toMatchSnapshot();
+    });
+});