Pytorch optimization

[luigibonati]

Description

• Add performance optimizations to PYTORCH (torch jit freeze and optimize_for_inference)
• Changed configure to link also CUDA-enabled libtorch libraries if available (requested by @maxbonomi)
• Moved instructions to link libtorch from the module PYTORCH page to the installation one.
• Updated LibTorch version tested in CI from 1.13 to 2.0

Target release

I would like my code to appear in release 2.10

Type of contribution

• changes to code or doc authored by PLUMED developers, or additions of code in the core or within the default modules
• changes to a module not authored by you
• new module contribution or edit of a module authored by you

Copyright

• I agree to transfer the copyright of the code I have written to the PLUMED developers or to the author of the code I am modifying.

• the module I added or modified contains a COPYRIGHT file with the correct license information. Code should be released under an open source license. I also used the command cd src && ./header.sh mymodulename in order to make sure the headers of the module are correct.

Tests

• I added a new regtest or modified an existing regtest to validate my changes.
• I verified that all regtests are passed successfully on GitHub Actions.