support for KaiOS mozSytem: true

[strukturart]

Hello,

would it be possible to add support for KaiOS, since KaiOS can use mozSystem: true to solve the CORS problem ?

https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/mozSystem

https://github.com/strukturart/greg/blob/6da3f2c87437598ebb009c38c2cdbb466f0cdaef/application/assets/js/tsdav.js#L603