kata-types: parse single_container OCI container type

ContainerType already renders as "single_container" via Display, but
from_str rejected it. Accept it so the value can round-trip, matching
the container type the Go runtime uses for standalone containers.

Signed-off-by: Fabiano Fidêncio <ffidencio@nvidia.com>
Assisted-by: Cursor <noreply@cursor.com>

src/libs/kata-types/src/container.rs

@@ -81,6 +81,7 @@ impl FromStr for ContainerType {
         match value {
             POD_CONTAINER | CONTAINER => Ok(ContainerType::PodContainer),
             POD_SANDBOX | PODSANDBOX | SANDBOX => Ok(ContainerType::PodSandbox),
+            SINGLE_CONTAINER => Ok(ContainerType::SingleContainer),
             _ => Err(Error::InvalidContainerType(value.to_owned())),
         }
     }
@@ -230,6 +231,10 @@ mod tests {
             ContainerType::from_str("sandbox").unwrap(),
             ContainerType::PodSandbox
         );
+        assert_eq!(
+            ContainerType::from_str("single_container").unwrap(),
+            ContainerType::SingleContainer
+        );
         ContainerType::from_str("test").unwrap_err();
     }