Support per-pod DNS settings

[nmittler]

The DNS proxy needs a way to identify per-pod DNS settings when running as a shared (multi-tenant) proxy. The initial implementation will use the settings defined the ztunnel DaemonSet's /etc/resolv.cof for all clients running on the node. While this will likely work for most use cases, we also need to respect per-pod settings.

[MorrisLaw]

This seems like a good issue for me to get deeper on Ztunnel to help further my understanding. Can I assign this to myself @nmittler @bleggett ?

[MorrisLaw]

Also, I think initial implementation in the description should link to this: #536

[nmittler]

@MorrisLaw sure, go for it!

[MorrisLaw]

RFC link: https://docs.google.com/document/d/1P2q7VnqFDZF4Ght913wtvVRuXHF3keJItbd8UENsvu4

[MorrisLaw]

As per the discussion in today's Ambient meeting. We'll be pausing work on this for now.