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/additional.rs

@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: MIT
+//
+// Copyright IBM Corp. 2024
+
+use crate::exchange::ExchangeFormatResponse;
+use anyhow::Result;
+use pv::attest::{AdditionalData, AttestationFlags};
+use serde::Serialize;
+use std::fmt::Display;
+use utils::HexSlice;
+
+#[derive(Serialize)]
+pub struct AttestationResult<'a> {
+    pub cuid: HexSlice<'a>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub add: Option<HexSlice<'a>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub add_fields: Option<AdditionalData<HexSlice<'a>>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub user_data: Option<HexSlice<'a>>,
+}
+
+impl<'a> AttestationResult<'a> {
+    pub fn from_exchange(
+        resp: &'a ExchangeFormatResponse,
+        flags: &AttestationFlags,
+    ) -> Result<Self> {
+        let add_fields = resp
+            .additional()
+            .map(|a| AdditionalData::from_slice_sized(a, flags))
+            .transpose()?;
+        Ok(Self {
+            cuid: resp.config_uid().into(),
+            add: resp.additional().map(|a| a.into()),
+            add_fields,
+            user_data: resp.user().map(|u| u.into()),
+        })
+    }
+}
+
+impl Display for AttestationResult<'_> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        writeln!(f, "Config UID:")?;
+        writeln!(f, "{:#}", self.cuid)?;
+        if let Some(data) = &self.add {
+            writeln!(f, "Additional-data:")?;
+            writeln!(f, "{:#}", data)?;
+        }
+        if let Some(data) = &self.add_fields {
+            writeln!(f, "Additional-data content:")?;
+            writeln!(f, "{:#}", data)?;
+        }
+        if let Some(data) = &self.user_data {
+            writeln!(f, "user-data:")?;
+            writeln!(f, "{:#}", data)?;
+        }
+        Ok(())
+    }
+}