cmake-rust: merge two RustStaticLibrary.cmake and add feature support
cmake-rust: merge two RustStaticLibrary.cmake and add feature support

Summary:
We somehow have two different RustStaticLibrary.cmake in different places (one in eden repo and the other one in the shared opensource builder).

This diff merges them and switches Eden into using the shared CMake function (for the features option).

This diff also adds the features option for rust_executable funciton, which will be used in the next diff.

Reviewed By: kmancini

Differential Revision: D39038491

fbshipit-source-id: 99d61a1d5450010b345107a9ec5c761b62004aa6

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