Migrate to cargo_embargo. am: 89738eb642 am: 7726e783b9 am: 55274aa4f4

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/mockall/+/2871119

Change-Id: Ie1f92994221d835391ec4b7cbb893e4a4e8985e8
Signed-off-by: Automerger Merge Worker <[email protected]>