Move VM callback to vmclient

Instead of having clients directly register a callback with VS,
implement a Rust level callback interface in vmclient. This saves an
extra binder call on each notification, a bunch of boilerplate code,
and allows us to provide a slightly better interface (e.g. we can use
the Rust DeathReason enum, as elsewhere in vmclient, for instantly
better logging).

I also replaced all our usages of <some_interface>::binder::{...} with
direct access to binder::{...}. That makes it clearer what depends on
the interface itself and what is just generic binder code. I realise
this should be a separate change, but I only realised that after doing
bits of both.

Test: composd_cmd test-compile, observe logs (on both success & failure)
Test: atest -b (to make sure all our tests build)
Test: Presubmits
Change-Id: Iceda8d7b8f8008f9d7a2c51106c2794f09bb378e
diff --git a/authfs/fd_server/src/aidl.rs b/authfs/fd_server/src/aidl.rs
index 0e8952e..9a60bf7 100644
--- a/authfs/fd_server/src/aidl.rs
+++ b/authfs/fd_server/src/aidl.rs
@@ -36,12 +36,12 @@
 use authfs_aidl_interface::aidl::com::android::virt::fs::IVirtFdService::{
     BnVirtFdService, FsStat::FsStat, IVirtFdService, MAX_REQUESTING_DATA,
 };
-use authfs_aidl_interface::binder::{
-    BinderFeatures, ExceptionCode, Interface, Result as BinderResult, Status, StatusCode, Strong,
-};
 use authfs_fsverity_metadata::{
     get_fsverity_metadata_path, parse_fsverity_metadata, FSVerityMetadata,
 };
+use binder::{
+    BinderFeatures, ExceptionCode, Interface, Result as BinderResult, Status, StatusCode, Strong,
+};
 
 /// Bitflags of forbidden file mode, e.g. setuid, setgid and sticky bit.
 const FORBIDDEN_MODES: Mode = Mode::from_bits_truncate(!0o777);