Remove support for macvtap with Firecracker

[richardcase]

Describe the solution you'd like:
Currently we use a forked version of Firecracker to get macvtap support. However, this feature isn't merged into main of Firecracker yet and its painful to continue to support a forked version.

Proposal:

• Remove usage of Forked firecracker version
• Update supported features to say macvtap is only supported with cloud hypervisor

Why do you want this feature:

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

[mmchougule]

@richardcase Anyone working on this? If possible, I would like to work to clean up firecracker and macvtap support for cloud hypervisor.

[richardcase]

@mmchougule - there is no one working on this yet, so that would be great if you wanted to work on it. I had a couple of thoughts on this that may help:

• We could introduce a new capability that a provider says if they support for macvtap.
  • Capabilities are defined here
  • The Firecracker & CloudHypervisor could publish whether they support macvtap (Firecracker doesn't but CH does). This is done using the Capabilities function on the provider interface
  • Somewhere in the core we'd need to check that an incoming microvm create request that the network interfaces if they have macvtap defined and if the provider doesn't support it then return an error
• There is a GHA workflow that checks for new firecracker versions and create an issue to update the fork. This can be deleted as we won't support the fork going forward
• Do you think it would be worth still checking for new Firecracker & Cloud Hypervisor releases and creating an issue for someone to check compatibility?
• Docs would need updating to remove mention of using the fork.

Feel free to ping me if you have any questions. We've also created a slack channel in the CNCF slack.

[richardcase]

@mmchougule - just checking in to see if you wanted to work on this? On pressure, if you don't then i will pick it up.