Allow users to configure any bottlerocket settings

[sp1999]

What would you like to be added:
I want the ability to modify any Bottlerocket settings at the time of cluster creation through the EKS-A cluster spec. Currently we support modifying only the kubernetes, kernel and boot settings.

Why is this needed:
This allows users to be able to edit Bottlerocket settings without having to make changes after cluster creation directly on the VMs. Some customers want to be able to specify the dns settings to configure the DNS servers for the host OS. We do have NTP configuration for the host OS currently to specify the time servers but not the DNS servers.