Add admin roles, user management, and campaign deletion

RpgRoller/Components/Pages/HomeControls/CampaignManagementPanel.razor

@@ -25,6 +25,13 @@
             <span class="add-row-icon" aria-hidden="true">+</span>
             <span>Add campaign</span>
         </button>
+
+        <button type="button"
+                class="ghost"
+                disabled="@(IsMutating || IsCreatingCampaign || !CanDeleteCampaign)"
+                @onclick="DeleteCampaignRequested">
+            Delete current campaign
+        </button>
     </section>
 
     <section class="card">