feat: Popup-Fenster für den Speicherort initialisiert.

- Schaltfläche im pspdf-kit-Symbolleistenmenü hinzugefügt.

EnvelopeGenerator.Web/Views/Home/ShowEnvelope.cshtml

@@ -127,6 +127,19 @@
             </div>
         </div>
     </div>
+    <div class="modal fade" id="locationBackdrop" data-bs-backdrop="static" data-bs-keyboard="false" tabindex="-1" aria-labelledby="locationBackdropLabel" aria-hidden="true">
+        <div class="modal-dialog">
+            <div class="modal-content">
+                <div class="modal-header">
+                    <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button>
+                </div>
+                <div class="modal-body">
+                </div>
+                <div class="modal-footer">
+                </div>
+            </div>
+        </div>
+    </div>
     }
     <div id='app'></div>
 </div>