Add router 4G model product

CHANGELOG:

### Added
- [#878](https://gitlab.com/coopdevs/odoo-somconnexio/-/merge_requests/878) Add router model ADOC R45 for router4G contracts

Related card: https://trello.com/c/TXrkbAkq/1355-nou-model-de-router-adocr45-adoc-r45-en-comptes-de-b311n-huawei-router-b311n

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