Move status report styling to its own library.

Closes #3511938

core/modules/navigation/tests/src/FunctionalJavascript/PerformanceTest.php

@@ -93,7 +93,7 @@ public function testLogin(): void {
       'ScriptCount' => 2,
       'ScriptBytes' => 215500,
       'StylesheetCount' => 1,
-      'StylesheetBytes' => 47700,
+      'StylesheetBytes' => 46300,
     ];
     $this->assertMetrics($expected, $performance_data);