fix: contact phone and fax import when values are empty

[alexhuk3]

What
Fixes contact phone and fax fields not being populated during import or refresh when the current state value is empty or unknown.

Why
When importing contacts, the API returns values for phone and fax, and also provides phone_normalized and fax_normalized.
However, the provider only populated the normalized fields, while phone and fax could remain empty in state.
This caused an extra update right after import.

How
During contact read:
always set phone_normalized and fax_normalized from the API response (contact.Phone / contact.Fax).
if phone and/or fax is empty, backfill it from the same API value (contact.Phone / contact.Fax) to avoid a post-import update