Upload file via auto-generated OpenAPI specification with gRPC backend #1

It seems that the support for the file upload with gRPC & OpenAPI generator is not very well.

1. The google.api.http has no annotation for file uploading...
2. The gRPC client streaming for file uploading is complicated...

Need to find a way to make it work because we need to send FileBox to our server...

Related Links

• Is there any way to support a multipart form request? grpc-ecosystem/grpc-gateway#410
• Handling Binary File Uploads grpc-ecosystem/grpc-gateway#500
• Usage demo about how to upload file/image by grpc-web? grpc/grpc-web#517 (comment)
• Lightweight support for custom protobuf annotations on RPCs grpc-ecosystem/grpc-gateway#1666
• StackOverflow: gRPC + Image Upload
• fix: typo of binary file update grpc-ecosystem/grpc-gateway#2258
• gRPC File Upload With Client Streaming