Added css bundle api. Improved css bundling code

I made the code cleaner as requested @Masu-Baumgartner  :>

Moonlight.Client/Startup.cs

@@ -134,9 +134,6 @@ public class Startup
         var assetManifest = await apiClient.GetJson<FrontendAssetResponse>("api/assets");
 
         var jsRuntime = WebAssemblyHost.Services.GetRequiredService<IJSRuntime>();
-
-        foreach (var cssFile in assetManifest.CssFiles)
-            await jsRuntime.InvokeVoidAsync("moonlight.assets.loadCss", cssFile);
         
         foreach (var javascriptFile in assetManifest.JavascriptFiles)
             await jsRuntime.InvokeVoidAsync("moonlight.assets.loadJavascript", javascriptFile);

Moonlight.Client/wwwroot/index.html

@@ -6,7 +6,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Moonlight.Client</title>
     <base href="/" />
-    <link rel="stylesheet" href="/css/core.min.css" />
+    <link rel="stylesheet" href="/css/bundle.css" />
     <link href="manifest.webmanifest" rel="manifest" />
     <link rel="apple-touch-icon" sizes="512x512" href="icon-512.png" />
     <link rel="apple-touch-icon" sizes="192x192" href="icon-192.png" />

Moonlight.Client/wwwroot/js/moonlight.js

@@ -27,15 +27,6 @@ window.moonlight = {
         }
     },
     assets: {
-        loadCss: function (url) {
-            let linkElement = document.createElement('link');
-
-            linkElement.href = url;
-            linkElement.rel = 'stylesheet';
-            linkElement.type = 'text/css';
-
-            (document.head || document.documentElement).appendChild(linkElement);
-        },
         loadJavascript: function (url) {
             let scriptElement = document.createElement('script');