Find CXX component for MPI, fortran and C are not needed

[aurianer]

Description

The default find_package is searching for all components. From the CMakeLists.txt I modified, you are linking only against MPI::MPI_CXX target. It is unnecessary to find the other C and Fortran mpi components.

Type of change

• Documentation change (change only to the documentation, either a fix or a new content)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Cleanup

[timmoon10]

This PR will be superceded by #760, but we should make sure to incorporate this PR at https://github.com/NVIDIA/TransformerEngine/pull/760/files#r1586537899.

[aurianer]

Once the change is backported there, feel free to close this PR :)

[aurianer]

Another way might be to merge this PR and do a rebase on main, I don't think this would create any conflicts :)