Show provider-supported codecs when creating a VoIP trunk

[Stell0]

The NethVoice trunk wizard always proposes G.729, A-law, and μ-law codecs, regardless of the selected provider.

Steps to reproduce

1. Open the NethVoice wizard.
2. Start creating a VoIP trunk.
3. Select a provider.
4. Open the codec selection.

Expected behavior

The wizard lists the codecs supported by the selected provider.

Actual behavior

The wizard always lists only G.729, A-law, and μ-law.

[andrea-marchionni]

PR testing image: ghcr.io/nethesis/nethvoice:pr-935.569-1.feec2ad

[Amygos]

Release nethesis/ns8-nethvoice 1.7.5