Handle multiple architectures when distributing airgap binary

[dereknola]

Changes

• Match architecture to what K3s release artifacts suffixes are.
• Handle arm/arm64 naming for the k3s binary artifacts.
  Note: This potentially allows for multiarch airgap clusters, if you download the appropriate artifacts for all relevant architectures, but I didn't explicitly test this. Your airgap folder would look something like

  ls -la ./playbooks/my-airgap/
  -rw-r--r-- 1 derek derek  68337816 Oct  7 11:24 k3s
  -rw-r--r-- 1 derek derek 175681141 Oct  7 11:24 k3s-airgap-images-amd64.tar.gz
  -rw-r--r-- 1 derek derek 132759685 Oct  7 11:04 k3s-airgap-images-arm64.tar.zst
  -rw-r--r-- 1 derek derek  63504536 Oct  7 11:04 k3s-arm64
  

Linked Issues

#365