rust/pvsecret: Refactor writing secret

Refactor the writing of secret-type dependent output files to ease
extensions.

Reviewed-by: Marc Hartmayer <marc@linux.ibm.com>
Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

rust/pv/src/uvsecret/guest_secret.rs

@@ -68,7 +68,7 @@ impl GuestSecret {
     }
 
     /// Reference to the confidential data
-    pub(crate) fn confidential(&self) -> &[u8] {
+    pub fn confidential(&self) -> &[u8] {
         match &self {
             Self::Null => &[],
             Self::Association { secret, .. } => secret.value().as_slice(),