EKSA Multiple OS Family Per Cluster

**What would you like to be added**:

EKS Anywhere to supports more than one OS family per cluster

**Why is this needed**:

Having EKS Anywhere to support more than one OS family per cluster will allow us to run it on a subset of nodes in our cluster with a small concession to the environment while keeping the hardened Bottlerocket security elsewhere.

The issue names no files, tests, or entry points. Start by locating the repository’s cluster OS-family handling and reviewing how Bottlerocket and other node operating systems are represented. Done should mean a cluster can intentionally use more than one OS family, with documented behavior and coverage for the mixed-OS case.

Written by the indexing model from the issue text.