Add initial c2a configuration. am: f2a65af3c6 am: 14d5ed960a

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/annotate-snippets/+/2638615

Change-Id: I91f3ae066b2f3bc08071a3a22fcb9e83de604983
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>