macOS requires setting of RPATH in executable solver

On macOS, and I suppose other BSD systems, one has to specify the `RPATH` for any third-party library used during the building of the solver because these libraries may be installed in various non-standard locations e.g. when using the Spack package manager to build the third-party libraries for `code_saturne`. In order to make this work I modified file `python/code_saturne/base/cs_case_domain.py` so that after the building of the solver is completed the code calls the `install_name_tool `utility that macOS has to add the required RPATHs to the executable.

The modification is changing the code starting from line 1007 checking if the platform is macOS and then calling this utility for each library path needed (only unique values should be used).

The modified file is attached to this issue report and it works properly on my system.

[cs_case_domain.py.zip](https://github.com/user-attachments/files/18508964/cs_case_domain.py.zip)

Start in python/code_saturne/base/cs_case_domain.py around line 1007, where solver building completes. Review the attached modification and the macOS install_name_tool utility, including how the required library paths are collected and deduplicated. Done means the built solver has the required RPATHs for third-party libraries installed in non-standard locations on macOS.

Written by the indexing model from the issue text.