[Feature Request] Core Scheduling

# Feature Request

It would be valuable to have core scheduling for Firecracker, to avoid, and potentially eliminate side channel attacks.

## Describe the desired solution

To add core scheduling to firecracker, and have it run the ioctl to set a new cookie for the vCPU processes.

## Describe possible alternatives

One can avoid using core scheduling by disabling SMT. Unfortunately, this means everything else on the system loses capacity, and if you're running VMs with more than 1 core, you can't take advantage of SMT.

## Checks

- [X] Have you searched the Firecracker Issues database for similar requests?
- [X] Have you read all the existing relevant Firecracker documentation?
- [X] Have you read and understood Firecracker's core tenets?