datastore: improve sync level code a bit

fixups for DatastoreFSyncLevel:
* use derive for Default
* add some more derives (Clone, Copy)

chunk store:
* drop to_owned for chunk_dir_path

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

pbs-api-types/src/datastore.rs

@@ -169,7 +169,7 @@ pub enum ChunkOrder {
 }
 
 #[api]
-#[derive(PartialEq, Eq, Serialize, Deserialize)]
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "lowercase")]
 /// The level of syncing that is done when writing into a datastore.
 pub enum DatastoreFSyncLevel {
@@ -181,6 +181,7 @@ pub enum DatastoreFSyncLevel {
     /// which reduces IO pressure.
     /// But it may cause losing data on powerloss or system crash without any uninterruptible power
     /// supply.
+    #[default]
     None,
     /// Triggers a fsync after writing any chunk on the datastore. While this can slow down
     /// backups significantly, depending on the underlying file system and storage used, it
@@ -198,12 +199,6 @@ pub enum DatastoreFSyncLevel {
     Filesystem,
 }
 
-impl Default for DatastoreFSyncLevel {
-    fn default() -> Self {
-        DatastoreFSyncLevel::None
-    }
-}
-
 #[api(
     properties: {
         "chunk-order": {