Explicitly add bin/compiler to path for oneapi and oneapi-ifx

[theurich]

Is your feature request related to a problem?

Yes. As it currently stands, e.g. after loading nautilus/oneapi-ifx-2025.3.0 on NRL Nautilus, the llvm-ar executable cannot be found. Projects often rely on this executable (and others that Intel keeps under bin/compiler). The current workaround is to explicitly edit add this path to the environment after loading the spack-stack module(s).

Describe the solution you'd like

Quoting @climbfuji: spack-stack to in general include the bin/compiler directory in the site config's compiler spec.

Additional context

This affects Navy-ESPC and NEPTUNE work at NRL.

[climbfuji]

Thanks! We'll try to get this into spack-stack-2.1.0