support multiple file operations

[boddumanohar]

build instructions:

https://github.com/0chain/zs3server
docker run --rm -v $PWD:/minio -v go-modules:/go/pkg/mod --workdir=/minio golang:1.18 go build
cd environment
make dev

zs3server improvements

* putObject -> multiple files
* getObject --> multiple files
* removeObject -> multiple files