feat: add --persist so SNO VM survives the host reboot

[xiormeesh]

When using miniagent/SNO instead of Openshift Local/crc sometimes the host needs to be rebooted without losing the SNO VM, this PR

• adds --persist flag defaulting to false
• enables autostart for both network and VM
• unmounts installation ISO file from the VM since it's stored in /tmp and would not survive a reboot
• copies /tmp/mini-agent/auth/kubeconfig to /var/lib/miniagent/kubeconfig (overwrites if exists but should not be an issue since miniagent supports only one SNO VM at a time anyway)

I've decided to gate the functionality behind --persist flag because based on our previous conversations most users need miniagent for quick tests and I wanted to keep the ephemeral usecase as is.

[andfasano]

Hi @xiormeesh thanks for your contribution (sorry the first commit somehow slipped through the cracks)!
It looks like a nice addition, I've just a comment on the dest folder, but for the rest looks fine

[andfasano]

For that I'd prefer using the user-specific data folder, ie:

miniagent_dir="${XDG_CONFIG_HOME:-$HOME/.config}/miniagent"

mkdir -p "$miniagent_dir"
install -m 600 "${assets_dir}/auth/kubeconfig" "$miniagent_dir/kubeconfig"