thumbnail: use a functional component

Simplifies the code a bit, and we use no lifecycle methods.

react/features/filmstrip/components/native/Thumbnail.js

@@ -1,6 +1,6 @@
 // @flow
 
-import React, { Component } from 'react';
+import React from 'react';
 import { View } from 'react-native';
 import type { Dispatch } from 'redux';
 
@@ -111,16 +111,10 @@ type Props = {
 /**
  * React component for video thumbnail.
  *
- * @extends Component
+ * @param {Props} props - Properties passed to this functional component.
+ * @returns {Component} - A React component.
  */
-class Thumbnail extends Component<Props> {
+function Thumbnail(props: Props) {
-    /**
-     * Implements React's {@link Component#render()}.
-     *
-     * @inheritdoc
-     * @returns {ReactElement}
-     */
-    render() {
     const {
         _audioMuted: audioMuted,
         _largeVideo: largeVideo,
@@ -134,7 +128,7 @@ class Thumbnail extends Component<Props> {
         participant,
         renderDisplayName,
         tileView
-        } = this.props;
+    } = props;
 
     const participantId = participant.id;
     const participantInLargeVideo
@@ -197,7 +191,6 @@ class Thumbnail extends Component<Props> {
 
         </Container>
     );
-    }
 }
 
 /**