use SVG icons for built-in tools (#2748)

api/core/tools/provider/builtin/youtube/_assets/icon.svg

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg width="800px" height="800px" viewBox="0 -38 256 256" version="1.1" xmlns="http://www.w3.org/2000/svg"
+     xmlns:xlink="http://www.w3.org/1999/xlink" preserveAspectRatio="xMidYMid">
+    <g>
+        <path d="M250.346231,28.0746923 C247.358133,17.0320558 238.732098,8.40602109 227.689461,5.41792308 C207.823743,0 127.868333,0 127.868333,0 C127.868333,0 47.9129229,0.164179487 28.0472049,5.58210256 C17.0045684,8.57020058 8.37853373,17.1962353 5.39043571,28.2388718 C-0.618533519,63.5374615 -2.94988224,117.322662 5.5546152,151.209308 C8.54271322,162.251944 17.1687479,170.877979 28.2113844,173.866077 C48.0771024,179.284 128.032513,179.284 128.032513,179.284 C128.032513,179.284 207.987923,179.284 227.853641,173.866077 C238.896277,170.877979 247.522312,162.251944 250.51041,151.209308 C256.847738,115.861464 258.801474,62.1091 250.346231,28.0746923 Z"
+              fill="#FF0000">
+        </path>
+        <polygon fill="#FFFFFF" points="102.420513 128.06 168.749025 89.642 102.420513 51.224">
+        </polygon>
+    </g>
+</svg>

api/core/tools/provider/builtin/youtube/youtube.yaml

@@ -9,7 +9,7 @@ identity:
     en_US: YouTube
     zh_Hans: YouTube（油管）是全球最大的视频分享网站，用户可以在上面上传、观看和分享视频。
     pt_BR: YouTube é o maior site de compartilhamento de vídeos do mundo, onde os usuários podem fazer upload, assistir e compartilhar vídeos.
-  icon: icon.png
+  icon: icon.svg
 credentials_for_provider:
   google_api_key:
     type: secret-input