feat: Add CSP configuration to use CSPMiddleware and CSP nonce to script tags in several cshtml script

EnvelopeGenerator.Web/Views/Home/EnvelopeLocked.cshtml

@@ -1,4 +1,7 @@
 @{
+    var nonce = _accessor.HttpContext?.Items["csp-nonce"] as string;
+}
+@{
     ViewData["Title"] = "Dokument geschützt";
     var userLanguage = ViewData["UserLanguage"] as string;
     var languages = ViewData["Languages"] as string[];
@@ -50,7 +53,7 @@
     </section>
 </div>
 <footer class="container" id="page-footer">&copy; SignFlow 2023-2024 <a href="https://digitaldata.works">Digital Data GmbH</a></footer>
-<script>
+<script nonce="@nonce">
     $(document).ready(function () {
         $('.select-flag').select2({
             templateResult: formatResult,

EnvelopeGenerator.Web/Views/Home/EnvelopeSigned.cshtml

@@ -1,7 +1,6 @@
 @{
     ViewData["Title"] = "Dokument unterschrieben";
 }
-
 <div class="page container p-5">
     <header class="text-center">
         <div class="icon signed">
@@ -12,10 +11,8 @@
         </div>
         <h1>Dokument erfolgreich signiert!</h1>
     </header>
-
     <section class="text-center">
         <p>Sie haben das Dokument signiert. Im Anschluss erhalten Sie eine schriftliche Bestätigung.</p>
     </section>   
 </div>
-
 <footer class="container" id="page-footer">&copy; SignFlow 2023-2024 <a href="https://digitaldata.works">Digital Data GmbH</a></footer>

EnvelopeGenerator.Web/Views/Home/ShowEnvelope.cshtml

@@ -1,4 +1,7 @@
-@using DigitalData.Core.DTO;
+@{
+    var nonce = _accessor.HttpContext?.Items["csp-nonce"] as string;
+}
+@using DigitalData.Core.DTO;
 @using EnvelopeGenerator.Application.DTOs;
 @model EnvelopeReceiverDto;
 @{
@@ -42,7 +45,7 @@
         </div>
     </div>
 </div>
-<script>
+<script nonce="@nonce">
     const collapseNav = () => {
         document.addEventListener('click', function (event) {
             var navbarToggle = document.getElementById('navbarToggleExternalContent');
@@ -66,7 +69,7 @@
 
     var envelopeKey = ViewData["EnvelopeKey"] as string;
 
-    <script>
+    <script nonce="@nonce">
         var base64String = "@Html.Raw(documentBase64String.TrySanitize(_sanitizer))";
         var byteCharacters = atob(base64String);
         var byteNumbers = new Array(byteCharacters.length);
@@ -82,5 +85,4 @@
         })
     </script>
 }
-
 <div id='app' style='background: gray; width: 100vw; height: 100vh; margin: 0 auto;'></div>