Add command to return the list of specs per deployment

[ferranbt]

There are two types of CRD specs that belong to a deployment: cluster and resource. We should be able to return for a specific deployment his specs alongside information of their state (completed, pending, canceled...).

This change requires the following changes:

• State: We need to add an index to keep track an index of spec -> deployment.
• Grpc: Add a Grpc endpoint.
• Cli: Add the command (name TBD).