Migrate to cargo_embargo. am: 8b829742b4

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/form_urlencoded/+/2822399

Change-Id: I86541aa49a7341701f731923dcfba55030510258
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>