Fix - allow searching by vat number in crm lead lines and contracts

CHANGELOG:

### Fix
- [#384](https://gitlab.com/coopdevs/odoo-somconnexio/-/merge_requests/384) Allow searching by DNI formatted VAT number in CRM Lead Line and Contract views. 

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So far, we could search by VAT number in CRMLeadLine and Contract view, but only with the entire VAT code. Was not possible with a DNI formatted number (without ES).

CRM - partner's DNI

CRM - SR's DNI

Contract - partner's DNI