add ads loading

packages/artplayer-plugin-ads/src/style.less

@@ -44,7 +44,7 @@
     }
 
     .artplayer-plugin-ads-control {
-        display: flex;
+        display: none;
         position: absolute;
         bottom: 10px;
         right: 10px;
@@ -64,4 +64,17 @@
             height: 20px;
         }
     }
+
+    .artplayer-plugin-ads-loading {
+        display: flex;
+        align-items: center;
+        justify-content: center;
+        position: absolute;
+        left: 0;
+        top: 0;
+        right: 0;
+        bottom: 0;
+        width: 100%;
+        height: 100%;
+    }
 }