Conformance tests for host context path expressions

[mwiebe]

Description

In bug fix OpenJobDescription/openjd-rs#207 it notes that the following conformance tests should detect the issue:

• https://github.com/OpenJobDescription/openjd-specifications/blob/mainline/conformance-tests/2023-09/EXPR/jobs/expr2.3.2--uri-path-ops.test.yaml

But they didn't! That's because the paths are evaluated at job submission time, which always uses POSIX paths.

We need a new conformance test just like that one, but that evaluates the paths in a host context. E.g. in the script let bindings instead of the step let bindings.