Enable support for creating EC keys using S3 API using STORAGE_IA storage class

[SaketaChalamchala]

Currently we support S3 APIs --storage-class=STANDARD, REDUCED_REDUNDANCY option to create keys with RATIS/THREE and RATIS/ONE replication.
To create EC keys the requirement currently is that the bucket has to be created with EC replication.

We could also support creating EC keys via S3 API by supporting --storage-class=STANDARD_IA (Standard Infrequent Access) and map it to ReplicationType.EC, null ReplicationFactor and accepting a custom metadata header(x-amz-meta-) for the replication config string.

Any thoughts on this?

https://docs.aws.amazon.com/cli/latest/reference/s3api/put-object.html

[errose28]

Summarizing some discussion from the community sync today:

We can use headers to support all types of replication regardless of which storage class is given. For convenience, we can make the server side replication used for STANDARD, REDUCED_REDUNDANCY, and STANDARD_IA configurable with default values as well. The server should return errors for storage classes which are not supported.