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>

proxmox-backup-client/src/mount.rs

@@ -240,7 +240,7 @@ async fn mount_do(param: Value, pipe: Option<Fd>) -> Result<Value, Error> {
         client,
         crypt_config.clone(),
         repo.store(),
-        &backup_type,
+        backup_type,
         &backup_id,
         backup_time,
         true,