Update StatusBody to support gRPC trailers

Change StatusBody from a tuple struct to a struct containing both data
and trailers. Update the codegen to use the new StatusBody::new
constructor to specify gRPC status codes.

Also remove the temp_test_project.

Cargo.lock

@@ -1196,6 +1196,7 @@ version = "0.1.0"
 dependencies = [
  "bytes",
  "futures-util",
+ "http",
  "http-body",
  "http-body-util",
  "prost",
@@ -1352,23 +1353,6 @@ version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0bf256ce5efdfa370213c1dabab5935a12e49f2c58d15e9eac2870d3b4f27263"
 
-[[package]]
-name = "temp_test_project"
-version = "0.1.0"
-dependencies = [
- "bytes",
- "futures-util",
- "http",
- "http-body",
- "http-body-util",
- "roto-codegen",
- "roto-runtime",
- "roto-tonic",
- "tokio-stream",
- "tonic",
- "tower 0.4.13",
-]
-
 [[package]]
 name = "tempfile"
 version = "3.27.0"