Validate Type for storage backends

[pkosiec]

Description

Add additional validation into our CLI manifest validation (capact manifest validate):

• Validate Type manifests according to the convention described in the Delegated storage proposal
• Check if the JSON schema meet our conditions for every Type with additionalRefs: ["cap.core.type.hub.storage"] when --server-side flag is provided
• Use some internal JSON schema for validation

Reason and use cases

See #688