build: include go_package mapping for csi.proto

[nixpanic]

Generating Go code from the .proto files gives a deprecation warning when csi.proto is imported. By passing the M option on the commandline to the generators, the warning is addressed.

See-also: https://developers.google.com/protocol-buffers/docs/reference/go-generated#package

[nixpanic]

The warning can be observed in recent (successful) executions of the protoc workflow:

# generate libs
cd .. && ./bin/protoc --go_out=lib/go --go_opt=paths=source_relative --plugin=./bin/protoc-gen-go replication/replication.proto
2023/06/28 13:11:22 WARNING: Deprecated use of 'go_package' option without a full import path in "github.com/container-storage-interface/spec/lib/go/csi/csi.proto", please specify:
	option go_package = "github.com/container-storage-interface/spec/lib/go/csi";
A future release of protoc-gen-go will require the import path be specified.
See https://developers.google.com/protocol-buffers/docs/reference/go-generated#package for more information.

cd .. && ./bin/protoc --go-grpc_out=lib/go --go-grpc_opt=paths=source_relative --plugin=./bin/protoc-gen-go-grpc replication/replication.proto
2023/06/28 13:11:22 WARNING: Deprecated use of 'go_package' option without a full import path in "github.com/container-storage-interface/spec/lib/go/csi/csi.proto", please specify:
	option go_package = "github.com/container-storage-interface/spec/lib/go/csi";
A future release of protoc-gen-go will require the import path be specified.
See https://developers.google.com/protocol-buffers/docs/reference/go-generated#package for more information.

Runs with this PR do not have these warnings anymore.