[attestation] Validate vendor module loaded by client VM in RKP VM

This cl added the following tasks to the RKP VM:

- Parses a client VM DICE chain containing an additional vendor
module entry.
- Validates the code hash in the vendor module DICE entry against
the code hash read from the device tree.

The cl also adds a CTS test that triggers the VM attestation from
a VM with vendor module.

Bug: 330678211
Test: atest MicrodroidTests
Change-Id: Id56c6edd8baa32bae6a8ad7b5bca7b18ce167022
diff --git a/service_vm/requests/src/lib.rs b/service_vm/requests/src/lib.rs
index 0dfac09..36b006f 100644
--- a/service_vm/requests/src/lib.rs
+++ b/service_vm/requests/src/lib.rs
@@ -26,4 +26,4 @@
 mod pub_key;
 mod rkp;
 
-pub use api::process_request;
+pub use api::{process_request, RequestContext};