refactor: Update video element in Artplayer to support custom canvas or video

docs/assets/example/canvas.js

@@ -1,8 +0,0 @@
-// npm i artplayer-plugin-canvas
-// import ArtplayerPluginCanvas from 'artplayer-plugin-canvas';
-
-var art = new Artplayer({
-    container: '.artplayer-app',
-    url: '/assets/sample/video.mp4',
-    Canvas: ArtplayerPluginCanvas,
-});

docs/assets/example/libmedia.js

@@ -0,0 +1,10 @@
+// npm i artplayer-proxy-libmedia
+// import artplayerProxyLibmedia from 'artplayer-proxy-libmedia';
+
+var art = new Artplayer({
+    container: '.artplayer-app',
+    url: '/assets/sample/video.mp4',
+    proxy: artplayerProxyLibmedia({
+        //
+    }),
+});

docs/assets/example/webav.js

@@ -0,0 +1,10 @@
+// npm i artplayer-proxy-webav
+// import artplayerProxyWebAV from 'artplayer-proxy-webav';
+
+var art = new Artplayer({
+    container: '.artplayer-app',
+    url: '/assets/sample/video.mp4',
+    proxy: artplayerProxyWebAV({
+        //
+    }),
+});