feat(tvix/store/blobservice): add GRPCBlobServiceWrapper

This takes a BlobService and ChunkService in the constructor, and
provides a [proto::blob_service_server::BlobService] trait for it.

Implementing proto::blob_service_server::BlobService is a lot of surface
to cover, and providing this wrapper will make individual
implementations taking care of how to store chunks or chunking
information much simpler.

Change-Id: Ia7b46484fb3ac9104354d496ff2922dca96ff7b9
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8092
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI

tvix/store/src/proto/mod.rs

@@ -7,6 +7,9 @@ use prost::Message;
 
 use nix_compat::store_path::{ParseStorePathError, StorePath};
 
+mod grpc_blobservice_wrapper;
+pub use grpc_blobservice_wrapper::GRPCBlobServiceWrapper;
+
 tonic::include_proto!("tvix.store.v1");
 
 #[cfg(feature = "reflection")]