Add Eltex model and TTP template

- Introduced a new `Eltex` model for parsing Eltex devices.
- Created a corresponding TTP template for Eltex devices, defining required and optional groups for configuration parsing.

oxi/interfaces/models/qtech.py

@@ -1,4 +1,3 @@
-from ipaddress import ip_interface
 import os
 from oxi.interfaces import register_parser
 from oxi.interfaces.base import BaseDevice