rust/pvattest: Add check command

Add a new command: check. This allows users to perform policy checks on
the Attestation result.
The host-key hashes, and the user-data can be tested for certain values.

While at it fix some typos and enable CSV parsing for the Additional-data flags.

Example:
```
pvattest check attestresp checkresult -k hkd0.crt,hkd1.crt
--host-key-check AttKeyCheck
```
Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>

rust/pvattest/src/cmd.rs

@@ -2,11 +2,13 @@
 //
 // Copyright IBM Corp. 2024
 //
+pub mod check;
 pub mod create;
 #[cfg(target_arch = "s390x")]
 pub mod perform;
 pub mod verify;
 
+pub use check::check;
 pub use create::create;
 pub use verify::verify;