Import protobuf-json-mapping crate. am: bb8920e11b am: daeeea76da am: 52c5d139a8 am: e42e8d5c1c am: 75a72ef204

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/protobuf-json-mapping/+/2514115

Change-Id: I6cbf6cf90b926aac2374050b7dcf8201f02b7770
Signed-off-by: Automerger Merge Worker <[email protected]>