Rust Crate support

A list of the available Crate binaries: https://conan.compiler-explorer.com/libraries_rust.html

Some notes:
* Rust libraries are supported through pre-built binaries for the default platform `x86_64`.
* None of the libraries are available for other platforms, and they will not be built automatically.
* We have not tested all the libraries. If anything seems out of the ordinary, let us know so that we can investigate.
* Be sure to select the library you want to use and then also use `extern crate cratename;` in your code

The crate binaries are mostly built by Cargo with the `--all-features` option. This means that either the create successfully built with all features are enabled, or it failed to build and the crate is not available. We have a limited selection of crates without any features enabled because `--all-features` failed to build, but not yet consistently.