Support for etcd snapshot and restore

[davidnuzik]

Add support for RKE2 snapshot, backup, and restore via Rancher via CLI.

• must also take automatic snapshots periodically.
• On by default
• Controlled via config args
• Supports S3 (need this capability similar to RKE1) Not need for 1.0
• Restore functionality folded into rke2 --cluster-reset - You restore by triggering a cluster-reset with a restore path arg specifified

[rancher-max]

Using rke2 beta16 to validate:

• Overall the flags are working well
• Cluster backups from local work as expected
  • Note that when doing local backups, if the node(s) that were specified to contain a local backup are deleted, then those backups are also lost.
• Must install from binary instead of install script if wanting the ability to use backups: Installing via install script causes cluster to continuously retry running rke2.service after quorum loss #293
• Not working in k3s for some reason: cluster fails to start with embedded etcd k3s-io/k3s#2201

[rancher-max]

• This has now been fully validated in k3s
• Going to do another round of validations in rke2, especially regarding quorum loss scenario, and then can close assuming that works as expected.
• One minor issue regarding logging opened: [Logging Issue] Incorrect flag in logs after resetting cluster using a restore-path k3s-io/k3s#2244

[rancher-max]

I think the support for etcd snapshot and restore is functional. There are a few issues that came from testing this that should be addressed on their own at this point.
Namely #320 and #353