UE Version:
UE5.6

Frontend Version:
E.g. UE5.5-1.2.4

Problem component
Frontend

Description
When loading pixel streaming in an iframe and you don't have the allow="xr-spatial-tracking" the dom will throw an Exception when trying to read the property .xr

SecurityError: Failed to execute 'isSessionSupported' on 'XRSystem': Access to the feature "xr" is disallowed by permissions policy.

Steps to Reproduce:

1. create an iframe an embed a pixel streaming app in it.

Expected behavior
We should wrap the navigator.xr.isSessionSupported() call in a try catch block so that we don't get an error if we are in an iframe.