Use 'filesystem-path' arbitrary descriptor for attributes/params that represent a path

Attribute/parameter descriptions allow "arbitrary descriptors".[1]
Perhaps we could add something like this to that list:

filesystem-path – boolean – indicates the attribute value represents a filesystem
path. The absence of this item implies false.

The CLI could then check for that and help the user with escaping if true. Currently CLI users need to escape '\' in low-level operation values, but they don't in commands. It's not necessary in commands because the CLI statically knows what the command is about; with a low level operation it can only do things based on the metadata provided by the server.

We can't guarantee that every 'path' attribute would have that set
properly though. So it's not a guarantee.

This is really a cross-request between WFCORE and WFLY; WFCORE with the needed base support and then configuring any relevant params/attributes in both code bases.

Also, consider other similar cases – 'url' as a possible example.

[1] https://docs.jboss.org/author/display/WFLY9/Admin+Guide#AdminGuide-ArbitraryDescriptors