NethVoice : Add support for Fanvil V50G phone model

[viktec]

Description

A request has been received to add the Fanvil V50G to the list of supported phone models. The goal is to make the model selectable/configurable and ensure correct provisioning behavior according to the platform’s supported phones workflow.

Steps to reproduce

1. Open the phones/handsets management area (provisioning UI).
2. Try to add/register a new phone model.
3. Search for “Fanvil V50G” in the available models list.
4. Attempt to provision/configure the device using the standard provisioning flow.

Expected behavior

• “Fanvil V50G” is available among supported models.
• Provisioning templates/config generation works for V50G and produces a valid configuration for the device.
• The device successfully boots and registers using the generated provisioning.

Actual behavior

• Fanvil V50G is not available / not supported (no model entry and no provisioning template).

[viktec]

nethesis/tancredi#373