Introducing C++20 build for some backends in CI

[yasahi-hpc]

Improves #80

This PR aims at adding C++20 build for THREADS, CUDA and HIP backend in CI,
as a preparation to test some C++20 features like std::source_location (See #122)

Following modifications are made

• C++20 build for THREADS, CUDA and HIP backend in CI.
• Enable ROCFFT for room build not for hip build

[cedricchevalier19]

LGTM