[Snaps] Extend microVM snapshot compatibility

# Feature Request

Allow to use a snapshot of a microVM in any supported architecture minimizing the need of different snapshots for different architecture and a more seamless usage of snapshots for a user.
This issue will track the activity to support such feature, including documentation update, definition of compatibility matrix and tests.

## Describe the desired solution

This feature allow to take a snapshot of a microVM on a supported architecture and allow Firecracker to resume the microVM on a different supported architecture.

## Describe possible alternatives

there is no alternative at the moment.

## Additional context

`[Author TODO: Add additional context about this feature request here.]`

## 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?