Mark sandbox="allow-pointer-lock" not supported on iOS (#23952)

* Mark sandbox="allow-pointer-lock" not supported on iOS

Even if the token is parsed, it has no effect since the pointer lock API isn't supported:
https://developer.mozilla.org/en-US/docs/Web/API/Element/requestPointerLock#browser_compatibility

* Add comma

---------

Co-authored-by: Florian Scholz <fs@florianscholz.com>

html/elements/iframe.json

@@ -896,7 +896,9 @@
                 "safari": {
                   "version_added": "10.1"
                 },
-                "safari_ios": "mirror",
+                "safari_ios": {
+                  "version_added": false
+                },
                 "samsunginternet_android": "mirror",
                 "webview_android": "mirror"
               },