Show vodafone_id in Vodafone and Router4G contract form view

CHANGELOG:

### Added
- [#781](https://gitlab.com/coopdevs/odoo-somconnexio/-/merge_requests/781) Show vodafone_id in Vodafone and Router4G contract form view.

Related card: https://trello.com/c/8TRrIJMF/1223-contractes-4g-camp-vodafone-id

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