nixos-modules: move virtiofsd from host to microvm

[astro]

@SuperSandro2000 Can you review pls? Note the simplified virtiofsdCount logic.

[MarcelCoding]

Lgtm, did not test

[MarcelCoding]

How should the migration be done. All vms need to be stopped, mcirovm on the host needs to be updated, all vms need to be rebuilt and started.

[astro]

How should the migration be done. All vms need to be stopped, mciro m in the host needs to be updated, all vms need to be rebuild and started

No urgent requirement to stop VMs but they must be updated before they can be started again. Hence the warning that is output on host activation. My hope is that VMs are updated more frequently than hosts.

[MarcelCoding]

How about a check if the scripts exists and if yes output that a rebuild is required.

[MarcelCoding]

Or create a new major release.

[astro]

How about a check if the scripts exists and if yes output that a rebuild is required.

I am not sure I understand, the activationScript snippet does check for the scripts' existence.

Or create a new major release.

I've prepared the CHANGELOG.md entries for that but let's wait a bit for any regressions.