api-types: introduce BackupType enum and Group/Dir api types

The type is a real enum.

All are API types and implement Display and FromStr. The
ordering is the same as it is in pbs-datastore.

Also, they are now flattened into a few structs instead of
being copied manually.

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

src/bin/proxmox-backup-manager.rs

@@ -523,7 +523,7 @@ pub fn complete_remote_datastore_group(_arg: &str, param: &HashMap<String, Strin
                 .await
         }) {
             for item in data {
-                list.push(format!("{}/{}", item.backup_type, item.backup_id));
+                list.push(format!("{}/{}", item.backup.ty, item.backup.id));
             }
         }
     }