Fixes rendering of the font icons used for buttons in the code editor. (#18053)

Author: AndyButland

src/Umbraco.Web.UI.Client/src/css/umb-css.css

@@ -3,3 +3,9 @@
 	--umb-header-layout-height: 70px;
 	--umb-section-sidebar-width: 300px;
 }
+
+@font-face{
+	font-display:block;
+	font-family:codicon;
+	src:url('/umbraco/backoffice/assets/fonts/codicon/codicon.ttf') format("truetype")
+}

src/Umbraco.Web.UI.Client/src/rollup.config.js

@@ -54,6 +54,7 @@ console.log('--- Copying TinyMCE i18n done ---');
 console.log('--- Copying monaco-editor ---');
 cpSync('./node_modules/monaco-editor/esm/vs/editor/editor.worker.js', `${DIST_DIRECTORY}/monaco-editor/vs/editor/editor.worker.js`);
 cpSync('./node_modules/monaco-editor/esm/vs/language', `${DIST_DIRECTORY}/monaco-editor/vs/language`, { recursive: true });
+cpSync('./node_modules/monaco-editor/min/vs/base/browser/ui/codicons', `${DIST_DIRECTORY}/assets/fonts`, { recursive: true });
 console.log('--- Copying monaco-editor done ---');
 
 const readFolders = (path) => readdirSync(path).filter((folder) => lstatSync(`${path}/${folder}`).isDirectory());