[native] one-time setup for rust-C++ integration

Summary: some includes that only need to be done once. separating this out so that the subsequent diff in stack can be a standalone "dummy diff" for introducing new rust functions in native

Test Plan: tested in subsequent diff

Reviewers: jon, ashoat

Reviewed By: jon

Subscribers: tomek, atul

Differential Revision: https://phab.comm.dev/D7221