kata-type: Relax Mandatory source Field Check in Guest-Pull Mode

Previously, the source field was subject to mandatory checks. However,
in guest-pull mode, this field doesn't consistently provide useful
information. Our practical experience has shown that relying on this
field for critical data isn't always necessary.

In other aspect, not all cases need mandatory check for KataVirtualVolume.
based on this fact, we'd better to make from_base64 do only one thing and
remove the validate(). Of course, We also keep the previous capability to
make it easy for possible cases which use such method and we rename it
clearly with from_base64_and_validate.

This commit relaxes the mandatory checks on the KataVirtualVolume specifically
for guest-pull mode, acknowledging its diminished utility in this context.

Signed-off-by: alex.lyn <alex.lyn@antgroup.com>

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

@@ -387,7 +387,15 @@ impl KataVirtualVolume {
     pub fn from_base64(value: &str) -> Result<Self> {
         let json = base64::decode(value)?;
         let volume: KataVirtualVolume = serde_json::from_slice(&json)?;
+
+        Ok(volume)
+    }
+
+    /// Decode and deserialize a virtual volume object from base64 encoded json string and validate it.
+    pub fn from_base64_and_validate(value: &str) -> Result<Self> {
+        let volume = Self::from_base64(value)?;
         volume.validate()?;
+
         Ok(volume)
     }
 }
@@ -650,7 +658,8 @@ mod tests {
         volume.direct_volume = Some(DirectAssignedVolume { metadata });
 
         let value = volume.to_base64().unwrap();
-        let volume2: KataVirtualVolume = KataVirtualVolume::from_base64(value.as_str()).unwrap();
+        let volume2: KataVirtualVolume =
+            KataVirtualVolume::from_base64_and_validate(value.as_str()).unwrap();
         assert_eq!(volume.volume_type, volume2.volume_type);
         assert_eq!(volume.source, volume2.source);
         assert_eq!(volume.fs_type, volume2.fs_type);