Compute CMAKE_PROGRAM_PATH from returned json

[jcar87]

This might work to set this after the first call to find_package (as the known limitation).

The implementation in CMakeToolchain is:

        build_req = self._conanfile.dependencies.build.values()
        build_bin_paths = []
        for req in build_req:
            cppinfo = req.cpp_info.aggregated_components()
            build_paths.extend(cppinfo.builddirs)
            build_bin_paths.extend(cppinfo.bindirs)

This is just an approximation by relying on the json alone.