feat(virtio-pmem): add device configs and implementation

Add implementations of device, event handling, metrics.
Add device config and builder types for API use.

Signed-off-by: Egor Lazarchuk <[email protected]>

Author: ShadowCurse

src/vmm/src/devices/virtio/mod.rs

@@ -20,6 +20,7 @@ mod iov_deque;
 pub mod iovec;
 pub mod net;
 pub mod persist;
+pub mod pmem;
 pub mod queue;
 pub mod rng;
 pub mod test_utils;