Add web app manifest and icons for Foodsharing onboarding

FoodsharingSiegen.Server/Pages/_Layout.cshtml

@@ -8,6 +8,12 @@
     <meta charset="utf-8"/>
     <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
     <base href="~/"/>
+    <link rel="icon" type="image/png" href="/favicon-96x96.png" sizes="96x96" />
+    <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
+    <link rel="shortcut icon" href="/favicon.ico" />
+    <link rel="apple-touch-icon" sizes="180x180" href="/apple-touch-icon.png" />
+    <meta name="apple-mobile-web-app-title" content="Foodsharing Einarbeitungen" />
+    <link rel="manifest" href="/site.webmanifest" />
     <link rel="stylesheet" href="css/bootstrap/bootstrap.min.css"/>
     <link href="css/site.css" rel="stylesheet"/>
     <link href="FoodsharingSiegen.Server.styles.css" rel="stylesheet"/>

FoodsharingSiegen.Server/wwwroot/site.webmanifest

@@ -0,0 +1,21 @@
+{
+  "name": "Foodsharing Einarbeitungen",
+  "short_name": "FS Onboarding",
+  "icons": [
+    {
+      "src": "/web-app-manifest-192x192.png",
+      "sizes": "192x192",
+      "type": "image/png",
+      "purpose": "maskable"
+    },
+    {
+      "src": "/web-app-manifest-512x512.png",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "maskable"
+    }
+  ],
+  "theme_color": "#e8ffe2",
+  "background_color": "#f2ffe9",
+  "display": "standalone"
+}