Migrate to cargo_embargo. am: 8b829742b4 am: 82d036ae80 am: 5aaa785ad4

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

Change-Id: Ic10845d515af27550f385d7f089e5cbc5a280e65
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>