pv + tools: Introduce versioned HostKey and Keyslot enums

Add a HostKey enum (currently V1(PKey<Public>)) and introduce a
versioned Keyslot enum (V1(KeyslotV1)). Rename the existing Keyslot type
to KeyslotV1 to prepare for future format extensions.

Update pv, pvattest, pvimg, and pvsecret to use the new enums.

Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Timo Keller <tkeller@linux.ibm.com>
Signed-off-by: Marc Hartmayer <marc@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

rust/pv/src/req/hostkey.rs

@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: MIT
+//
+// Copyright IBM Corp.
+
+//! Host key types for UV requests
+
+use openssl::pkey::{PKey, Public};
+
+/// Versioned host keys container
+#[non_exhaustive]
+#[derive(Clone, Debug)]
+pub enum HostKey {
+    /// ECDH public key
+    V1(PKey<Public>),
+}
+
+impl HostKey {
+    /// Return the ECDH public key
+    pub fn ec_key(&self) -> &PKey<Public> {
+        match self {
+            HostKey::V1(ec_key) => ec_key,
+        }
+    }
+}
+
+impl AsRef<HostKey> for HostKey {
+    fn as_ref(&self) -> &HostKey {
+        self
+    }
+}