Library _file_ names in cpp_info.libs or cpp_info.system_libs do not work

[ravenexp]

When a Conan dependency package uses a plain library file name such as libfoo.a or libbar.so in its cpp_info.libs or cpp_info.system_libs package attributes, broken GNU linker flags are generated by conan2-based build scripts.

The build script is passing -llibfoo.a or -llibbar.so directly to the cc linker which then results in link failure.
Conan with CMake-based generators can handle linking of such dependency packages correctly.

The rustc link command generator should be able to recognize these use cases and pass static=foo or dylib=bar instead.

Reference: https://doc.rust-lang.org/cargo/reference/build-scripts.html#rustc-link-lib