User should be able to create/update a secret through apis & cli.

[sravankorumilli]

A user through apis or through CLI should be able to create/update the secrets such that he should be able to reference the secrets & use in the Optimus Jobs.

User should be provided an option to create secret at project or namespace level.

Acceptance Criteria

• GRPC end points to create/update a secret to accept base64 encoded values.
• CLI to create/update secrets to accept both base64 & plain text.
• Update documentation
• Secrets to be encrypted securely.