Add rust_test and update TEST_MAPPING am: 9185be9faf am: 3769ff0ea0 am: f80bd068a1

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/ppv-lite86/+/1365224

Change-Id: Iba6375982075fdb395abb6168f75d527958d7880