Provide quick fix for undefined property reference in server.xml

[cherylking]

If a property reference in server.xml is not defined within server.xml, bootstrap.properties or server.env, then provide a quick fix to create a variable with that property name in the server.xml file.

This is a future enhancement and not part of the MVP. Slide 28 of UFO.

[cherylking]

Should probably give the user options of where to create the variable - current xml file, bootstrap.properties, server.env, maybe even configDropins or the following location which I think is somewhat new for specifying variables:

[scottkurz]

Just noting that WDT/LDT has this support, at least for unresolved variable refs in server.xml, and it also seems to be applied to the merged config (include & dropins). Not that this moves us forwards a whole lot..just noting.

The WDT diagnostic would say something like:

 - The property 'destinationType', for the element 'properties.wasJms', contains an undefined variable reference 'abc'