Enhancement: twitter animated_gif autoplay (#1426)

- `media.type` 为 `animated_gif` 时自动循环播放视频，普通视频（`video`）维持原状
- 具体表现与阅读器（或者说是浏览器内核）有关，有些确实不支持自动播放，可以参考[这个](https://imququ.com/post/new-video-policies-for-ios10.html)
- Closes #1421

lib/routes/twitter/utils.js

@@ -36,7 +36,8 @@ const ProcessFeed = ({ data = [] }) => {
         }, {});
 
         if (video.url) {
-            content = `<br><video src="${video.url}" controls="controls" poster="${getOrigionImg(media.media_url_https)}" style="width: 100%"></video>`;
+            const gifAutoPlayAttr = media.type === 'animated_gif' ? `autoplay loop muted webkit-playsinline playsinline` : '';
+            content = `<br><video src="${video.url}" ${gifAutoPlayAttr} controls="controls" poster="${getOrigionImg(media.media_url_https)}" style="width: 100%"></video>`;
         }
 
         return content;