feat(conference) added React Navigation

Introduce navigation for all in-conference screens.

react/features/conference/components/native/HeaderNavigationButton.js

@@ -0,0 +1,39 @@
+// @flow
+
+import React from 'react';
+import { TouchableWithoutFeedback } from 'react-native';
+
+import { Icon } from '../../../base/icons';
+
+import styles from './styles';
+
+type Props = {
+
+    /**
+     * Callback to invoke when the {@code HeaderNavigationButton} is clicked/pressed.
+     */
+    onPress: Function,
+
+    /**
+     * The ImageSource to be rendered as image.
+     */
+    src: Object,
+
+    /**
+     * The component's external style
+     */
+    style: Object
+}
+
+const HeaderNavigationButton = ({ onPress, src, style }: Props) => (
+    <TouchableWithoutFeedback
+        onPress = { onPress } >
+        <Icon
+            size = { 20 }
+            src = { src }
+            style = { [ styles.headerNavigationButton, style ] } />
+    </TouchableWithoutFeedback>
+);
+
+
+export default HeaderNavigationButton;