Update Swashbuckle to v10 (#20925)

* Update Swashbuckle to v10

* Regenerate backoffice api client

* Add missing space for consistency

* Simplify nullability check

* Small improvement

Didn't notice that these classes were internal, so tried keeping compatibility, but it wasn't needed.

* Fix failing integration test

* Apply suggestions from code review

Co-authored-by: Andy Butland <abutland73@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Remove unnecessary comma

---------

Co-authored-by: Andy Butland <abutland73@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

tests/Umbraco.Tests.Integration/Umbraco.Core/DeliveryApi/OpenApiContractTest.cs

@@ -1596,7 +1596,15 @@ internal sealed class OpenApiContractTest : UmbracoTestServerTestBase
             "additionalProperties": { }
           }
         }
-      }
+      },
+      "tags": [
+        {
+          "name": "Content"
+        },
+        {
+          "name": "Media"
+        }
+      ]
     }
     """;
 }