add design doc for ClientProfileReplication

[rewantsoni]

Describe what this PR does

Add the design doc related to the new ClientProfileReplication CR

Is there anything that requires special attention

Provide any external context for the change, if any.

• doc: add design for replication destination info csi-addons/kubernetes-csi-addons#993
• replication: add specification of GetReplicationDestinationInfo csi-addons/spec#79
• feat: add design for replicationDestinationInfo ceph-csi#6316

Checklist:

• Commit Message Formatting: Commit titles and messages follow guidelines in the developer guide.
• Reviewed the developer guide on Submitting a Pull Request
• Pending release notes updated with breaking and/or notable changes for the next major release.
• Documentation has been updated, if necessary.
• Unit tests have been added, if necessary.
• Integration tests have been added, if necessary.

[iPraveenParihar]

@rewantsoni Need clarification.

[Madhu-1]

Couple of comments when i look at this as standalone design doc.

• The design doc should also point to the consumption model on how DR will update the volume Handles
• Migration path for existing clusters, Need to cover what happens on the upgraded cluster where we have PVC with old volumeHandle
• CO-existance behaviour of both Replicationdesitination and client profile mapping
• What happens if 2 ReplicationDestinationConfig contains same localClientProfile?
• What happens if ReplicationDestinationConfig contains same localClientProfile but there is no clientProfile with the name yet?
• Missing details of which configmap key will be updataed for this new CRD
• Controller high level design, How 2 controllers will coordinates as they need to update the same key contents in the same configmap
• How we are ensureing the tight couping between the new CR and the clientProfile. if the clientProfile CR is deleted the entries in configmap will also gets
  deleted even though we have ReplicationDestinationConfig
• Add a statement that poolNames are same across the clusters
• Add CRD defination as part of design
• Need to call out that design considered pool names as constamtt if ever pools are renamed. the corresponding details need to be updated on the CR as well.