api: disk list: sort by name

So callers get more stable results. Most noticeable, the disk list in
the web UI doesn't jump around upon reloading, and while sorting could
be done directly there, like this other callers get the benefit too.

Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>

src/api2/node/disks/mod.rs

@@ -66,6 +66,8 @@ pub fn list_disks(
         }
     }
 
+    list.sort_by(|a, b| a.name.cmp(&b.name));
+
     Ok(list)
 }