Request Document: go/android-rust-importing-crates
For CL Reviewers: go/android3p#cl-review
For Build Team: go/ab-third-party-imports
Bug: http://b/328180645
Test: m libdrm_rust (with aosp/2997556 checked out locally)

Change-Id: I32689719f1bd98740694b39e330518cba6b3e94d