[FEAT] Add share module in lib_ccxr

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{pull request content here}
This PR migrates the sharing service used by the cctranslate service. The first draft was added on 5/1/2025. The new rust Implentation is in /src/rust/lib_ccxr/src/share/.

Changes Made

• The Rust file containing the main translated logic is in /src/rust/lib_ccxr/src/share/share.rs
• The Rust file /src/rust/lib_ccxr/src/share/tests.rs contains some preliminary tests.
• The File /src/rust/src/libccxr_exports/share.rscontains the C bindings, as per doc specification
• The nanomsg library for rust is being used in this code, just like the nanomsg library is used in the C code. The tests have all ran successfully, although I feel like that the current tests may not be enough to test it out completely.
• I've also made some changes in the build commands of Linux and Mac to make them build successfully. It does for Linux, as far as I've tested.