Refactor interface linking system:

- Remove 'interface_connected_asset_interface' column usage
- Introduce 'asset_interface_links' table for one-to-one connections
- Update add/edit/delete queries and modals to handle new schema
- Exclude already-connected interfaces in dropdowns
- Improve data integrity and simplify linking logic

database_version.php

@@ -5,4 +5,4 @@
  * It is used in conjunction with database_updates.php
  */
 
-DEFINE("LATEST_DATABASE_VERSION", "1.7.8");
+DEFINE("LATEST_DATABASE_VERSION", "1.7.9");