This change uses the updated ldap library in minio/pkg (bumped
up to v3). A new config parameter is added for LDAP configuration to
specify extra user attributes to load from the LDAP server and to store
them as additional claims for the user.
A test is added in sts_handlers.go that shows how to access the LDAP
attributes as a claim.
This is in preparation for adding SSH pubkey authentication to MinIO's SFTP
integration.
Optionally allows customers to enable
- Enable an external cache to catch GET/HEAD responses
- Enable skipping disks that are slow to respond in GET/HEAD
when we have already achieved a quorum
