vm-migration: Use zerocopy for safe serialization

Getting rid of the unsafe ByteValued implementation for MemoryRange,
Request and Response structures, by relying on zerocopy's safe
implementation instead.

Signed-off-by: Sebastien Boeuf <sboeuf@meta.com>
Assisted-by: Claude:claude-opus-4-8

vm-migration/Cargo.toml

@@ -14,6 +14,7 @@ serde = { workspace = true, features = ["derive", "rc"] }
 serde_json = { workspace = true }
 thiserror = { workspace = true }
 vm-memory = { workspace = true, features = ["backend-atomic", "backend-mmap"] }
+zerocopy = { workspace = true, features = ["alloc", "derive"] }
 
 [lints]
 workspace = true