Allow login via alternative login methods

[mraerino]

It's likely that production users of Vault will use OIDC or similar login mechanisms instead of a Vault token for login.

We should add:

• A config option to specify what login process is desired
• Ability to renew tokens that allow it

[mraerino]

Fixed in https://github.com/ffddorf/netbox-vault-secrets/pull/17