Distro detection parity with containerd-shim-spin's installer

[vdice]

Describe your changes

Adds distro detection for parity with the current installer script used in SpinKube today (see containerd-shim-spin's installer script)

Incorporates changes from https://github.com/spinkube/runtime-class-manager/pull/84 and adds the following additional commits:

• adds setup functions for rke2/k3s
• adds k0s support
• misc refactor (simplified distro.Restarter)
• adds tests/testdata for DetectDistro and WithSetup

Notes

I used Lima VMs to test the following distros (links to their lima.yaml configs):

• k0s
• k3s
• rke2
• microk8s

For all of these, I used the quick start/easy mode for installation.

Untested and looking for volunteers to help out: GKE, EKS, DO K8s

Issue ticket number and link

https://github.com/spinkube/runtime-class-manager/issues/65

Supersedes https://github.com/spinkube/runtime-class-manager/pull/84

Checklist before requesting a review

• [x] I have performed a self-review of my code
• [x] If it is a core feature, I have added thorough tests.
• I tested the changes with the following distributions:
  • [x] Kind
  • [x] K3s
  • [x] K0s
  • [x] MiniKube
  • [x] MicroK8s
  • [x] Rancher RKE2
  • [x] Azure AKS
  • [ ] GCP GKE (Ubuntu nodes)
  • [ ] AWS EKS (AmazonLinux2 nodes)
  • [ ] AWS EKS (Ubuntu nodes)
  • [ ] Digital Ocean Kubernetes