[deprecate] use native `json-to-xml` functions where available

[duncdrum]

we can either deprecate src/main/xar-resources/modules/json-xml.xqm and bump a new minimum requirement for the api,

or we create a backwards compatible fix, where the current module is only used on instance, which don't support the native functions already based on the instances semVer.

[adamretter]

I would suggest that we just drop json-xml.xqm completely - I guess this will mean a few changes to the fusion-studio-extension too as the JSON may change subtly - so let's get CI for fusion-studio-extension finished first...