message: add Webview.cspSource content security policy
diff: @@ -125,7 +125,7 @@ export class ReactPanel {
  <meta name="theme-color" content="#000000">
  <title>Web Template Studio</title>
  <link rel="stylesheet" type="text/css" href="${this._panel.webview.asWebviewUri(stylePathOnDisk)}">
  - <meta img-src https: ;style-src 'unsafe-inline' http: https: data:;">
  + <meta img-src ${this._panel.webview.cspSource} https: ;style-src ${this._panel.webview.cspSource} 'unsafe-inline' http: https: data:;">
  <base href="${this._panel.webview.asWebviewUri(basePathOnDisk)}/">
  </head>
  <body>
  