Refactoring of devices management

There have been several discussions about the way devices, device resources and device managers need to coexist in Firecracker.
Here are some links:
- https://github.com/firecracker-microvm/firecracker/pull/4487#discussion_r1552065520
- https://github.com/firecracker-microvm/firecracker/pull/4428#discussion_r1509748674
- https://github.com/firecracker-microvm/firecracker/pull/4428#discussion_r1516203612
- https://github.com/firecracker-microvm/firecracker/pull/4428#discussion_r1527198460
- https://github.com/firecracker-microvm/firecracker/pull/4487#discussion_r1555937828

Because device management is one of the key components in Firecracker we should think about the way to improve our code quality in this area as it will help us with future addition of new devices.

For now this issue can be just a hub for all thought about this topic.

## Checks

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

Start by reviewing the device-management discussions linked from the issue, especially PRs 4487 and 4428. The issue names no files, tests, or entry points and describes only a discussion hub, so the scope and criteria for completion still need to be defined.

Written by the indexing model from the issue text.