Namespace declarations are not carried over from external schema fragments

[dmj]

For an example see Schematron/schematron-enhancement-proposals#62 (comment)

This should work: When include/extends an external Fragment we add sch:ns elements from the target document if present. We turn these sch:ns elements in namespace nodes during the transpile stage.

• Write a conformance test for this behavior
• Implement for SchXsl2 Core
• Implement for SchXslt
• Implement for SchXslt Redux XSLT 1
• Implement for SchXslt Redux XSLT 2

[dmj]

Note on implementation: Copying the sch:ns does not work if the include target is a sch:let variable with element content. This leaves converting sch:ns into xmlns pseudo attributes as the viable option.