refactor(pci): move PCI emulation logic in vmm mod

The implementation of the PCI emulation components is heavily
Firecracker opinionated. Move those inside a module of `vmm` crate and
leave in the `pci` module only type definitions which can easily be
reused across VMMs.

We also take advantage of this refactoring to remove in various places
the usage of `std::io::Error` as error types returned by emulation
logic.

Signed-off-by: Babis Chalios <[email protected]>

Author: bchalios

src/pci/Cargo.toml

@@ -12,17 +12,11 @@ bench = false
 default = []
 
 [dependencies]
-byteorder = "1.5.0"
 displaydoc = "0.2.5"
 libc = "0.2.175"
 log = "0.4.28"
 serde = { version = "1.0.226", features = ["derive"] }
 thiserror = "2.0.16"
-vm-device = { path = "../vm-device" }
-vm-memory = { version = "0.16.1", features = [
-  "backend-mmap",
-  "backend-bitmap",
-] }
 
 [dev-dependencies]
 serde_test = "1.0.177"