Implement GenericByteStreamMethodHandler and CodecMessageStreamHandler adapter

This commit introduces the `GenericByteStreamMethodHandler` trait to provide a standard interface for handling raw gRPC byte streams (`ReqB: Buf`).

Additionally, it adds the `CodecMessageStreamHandler`, which bridges the gap between raw byte streams and strongly-typed gRPC messages. It acts as an adapter that wraps an underlying `MessageStreamHandler` and implements `GenericByteStreamMethodHandler`, transparently managing the encoding and decoding of message streams using standard Codecs.

Finally, the `method_handler` module is updated to export these new components and introduces a `CodecRespB` type alias for the default codec response body type.

Author: sauravzg

grpc/src/server/method_handler.rs

@@ -9,6 +9,10 @@ pub use server_streaming_adapter::ServerStreamingAdapter;
 
 mod unary_adapter;
 pub use unary_adapter::UnaryMethodAdapter;
+mod generic_byte_stream_method_handler;
+pub use generic_byte_stream_method_handler::GenericByteStreamMethodHandler;
+mod codec_message_stream_handler;
+pub use codec_message_stream_handler::CodecMessageStreamHandler;
 
 mod message_stream_handler;
 pub use message_stream_handler::MessageStreamHandler;
@@ -18,3 +22,6 @@ pub use message_allocator::{
     HeapMessageAllocator, HeapMessageHolder, HeapRequestHolder, HeapResponseHolder,
     RpcMessageAllocator, RpcMessageHolder, RpcRequestHolder, RpcResponseHolder,
 };
+
+/// The default response body type produced by standard Codecs.
+pub type CodecRespB = bytes::Bytes;