chart rig-operator: generate certificates for webhooks

[blacksails]

The rig-operator cli has been extended with a command for certificate generation. This can be used in helm pre/post hooks to setup the certificate for the CRD webhook.

TODO:

• Command to be run as a helm pre/post install job which generates and patches relevant resources #656
• Command to be run as a helm post-install job to verify that the rig-operator api is ready, before proceeding #667
• Add option of patching CRDs. Currently we only patch the *WebhookConfiguration objects which means that we dont register the CA for the conversion webhook (this is registered on the CRD resource. #670
• Add apicheck post-install hook. This will ensure that the APIs provided by rig-operator are ready for use. #671
• Add helm pre-install hook for generating certificates #679
• Add helm post-install hook for patching webhook configuration with CA certificate #679