Wrong SOFA binary folder on Windows

[alxbilger]

In https://github.com/sofa-framework/SofaPython3/blob/master/bindings/Sofa/package/init.py, the code checks the existence of files relative to SOFA_ROOT. However, on Windows, the bin folder is not sofa_root + "\\bin", but sofa_root + "\\bin\\<COMPILATION_MODE>". For example bin/RelWithDebInfo, bin/Release or bin/Debug. Therefore, the variables sofa_bin_path and sofapython3_bin_path are wrongly defined.