Traefik IPWhiteList deprecated - Use IPAllowList Instead

[nickjones33]

What this PR does / why we need it:
Updates references from the deprecated IPWhiteList Traefik middleware to use IPAllowlist instead, so that we don't get deprecation warnings from Traefik

Which issue (if any) this PR fixes:

Fixes #703

Any other useful info:

[nickjones33]

I'm not super familiar with the typical github and/or ansible-nas-specific PR process so please let me know if I need to make any changes here, I will monitor this PR and respond to feedback accordingly.

I noticed Issue #703 sitting out there and figured I could make a PR pretty quickly for it

[davestephens]

This is a good change, thank you.

It has been implemented in a way that will break people with no warning though - please can you add a check for the *whitelist variables being set in the relevant roles, and throw an error if so? You'll find equivalent checks for variables in Drone role, if you need something to use as a reference.

[nickjones33]

Thanks for the Drone role example, I hope I've followed it as you expected. I set default values in the *whitelist variables of "deprecated" and threw the builtin.fail if the setting had been changed.

[davestephens]

Thanks - getting there! You should be able to use is defined rather than check for specific content of the variable. This will enable removing of the *whitelist variables from the variables now, leaving only the check you've put in as the remnants of any *whitelist stuff.

[nickjones33]

That makes much more sense!

[davestephens]

Awesome, thank you! 👍