[IMP] Link existing mobile contracts with new fiber

CHANGELOG:

### Added
- [#1071](https://git.coopdevs.org/coopdevs/som-connexio/odoo-somconnexio/-/merge_requests/1071) Link fiber contract with existing new mobile pack contracts without fiber linked, if found in the same CRMLead

Related card: https://trello.com/c/IRU4M70y/1785-permetre-creaci%C3%B3-contractes-m%C3%B2bil-alta-nova-apinyats-abans-activaci%C3%B3-fibra

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