feat: Consume UFM credentials from config file/env variables

[Matthias247]

Is this a new feature, an enhancement, or a change to existing functionality?

New Feature

How would you describe the priority of this feature request

Medium

Please provide a clear description of problem this feature solves

In order to remove the Vault dependency from NICo (#195), NICo should no longer retrieve UFM credentials from Vault.

Feature Description

NICo should read read the credentials from a file referenced in its config files.
The content can be written there in any way the operator desired. However in most cases it is expected to get injected. E.g. it might be a k8s secret.

NICo should reload the file if necessary so that credentials can be updated during NICo runtime.

Describe your ideal solution

No response

Describe any alternatives you have considered

No response

Additional context

No response

Code of Conduct

• I agree to follow NCX Infra Controller's Code of Conduct
• I have searched the open feature requests and have found no duplicates for this feature request

[Matthias247]

It's possible that this was somewhat already achieved with #357. However it doesn't seem to be used so far. Maybe the documentation for how the new feature is working are lacking?