POSIX: Implement performant filesystem layer/view of DSS S3 object storage

Currently DSS Support S3 based APIs to acccess the cluster.
rclone and s3fs are some of the implementations, but they severely degrade the DSS performance.

We need to add filesystem/posix layer for this S3 storage APIs, which is also performant
This is highly useful for traditional applications using filesystems for their storage requirements.