test_infra: Implement Display for GuestVmType

Add Display trait implementation for GuestVmType to enable
formatted output of the VM type in logs and diagnostics.

Signed-off-by: Muminul Islam <muislam@microsoft.com>

test_infra/src/lib.rs

@@ -7,7 +7,7 @@
 
 use std::collections::HashMap;
 use std::ffi::OsStr;
-use std::fmt::Display;
+use std::fmt::{Display, Formatter};
 use std::fs::OpenOptions;
 use std::io::{Read, Seek, SeekFrom, Write};
 use std::net::{TcpListener, TcpStream};
@@ -2505,6 +2505,15 @@ impl FromStr for GuestVmType {
     }
 }
 
+impl Display for GuestVmType {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        match self {
+            GuestVmType::Regular => write!(f, "regular"),
+            GuestVmType::Confidential => write!(f, "confidential"),
+        }
+    }
+}
+
 // Get the direct igvm boot file path based on the console type
 fn direct_igvm_boot_path(console: Option<&str>) -> Option<PathBuf> {
     // get the default hvc0 igvm file if console string is not passed