feat: allow skip pass trailers in nginx grpc upstream

[bzp2010]

Add a patch to the nginx upstream module to allow grpc_pass to be used without upstream trailers being passed through to the client.

For apache/apisix#11988

[Copilot]

Pull Request Overview

This pull request adds support to use gRPC without passing upstream trailers by introducing a gRPC server implementation for testing purposes. The changes include a new gRPC server written in Go (server.go), protocol definitions (route.proto) along with generated code (route.pb.go), and a CI configuration update to run the required gRPC setup script.

Reviewed Changes

Copilot reviewed 5 out of 13 changed files in this pull request and generated no comments.

File	Description
t/assets/grpc/server.go	Introduces a simple gRPC server implementation for routing.
t/assets/grpc/a6/route.proto	Defines the protocol for route queries and responses.
t/assets/grpc/a6/route.pb.go	Generated Go code for the defined protobuf messages and service.
.github/workflows/ci.yml	Updates CI workflow to run an additional setup script for gRPC.

Files not reviewed (8)

• lib/resty/apisix/upstream.lua: Language not supported
• patch/1.25.3.1/nginx-upstream_pass_trailers.patch: Language not supported
• patch/1.27.1.1/nginx-upstream_pass_trailers.patch: Language not supported
• src/ngx_http_apisix_module.c: Language not supported
• src/ngx_http_apisix_module.h: Language not supported
• t/assets/grpc/go.mod: Language not supported
• t/assets/grpc/setup.sh: Language not supported
• t/upstream_pass_trailers.t: Language not supported

Comments suppressed due to low confidence (2)

t/assets/grpc/server.go:40

• [nitpick] Consider clarifying the error message to be more descriptive, e.g., 'Route name cannot be empty'.

return nil, status.Errorf(codes.InvalidArgument, "query params invalid")

.github/workflows/ci.yml:35

• Ensure that the 'setup.sh' script exists at the specified path to avoid CI failures.

cd t/assets/grpc && ./setup.sh > build.log 2>&1 || (cat build.log && exit 1) && cd ../../..

[bzp2010]

GM test failure has nothing to do with the current PR, so please ignore it.