Implement the interface for the secrets

[Dr0p42]

We need to implement the cli and sdk interface for the secret api: https://api.naas.ai/docs#/secret

We need from the CLI and from the SDK to be able to:

• List secrets
• Create or Update secrets.
• Get a secret
• Delete a secret

So it means that in this project we need to create a new secret domain with the required adapters, handlers etc.

This will benefit terminal users but also ourselves in the way we build ABI and any future products.