Add service province to contract search view

CHANGELOG:

### Added
- [#656](https://gitlab.com/coopdevs/odoo-somconnexio/-/merge_requests/656) Add service state to contract search view

Related card: https://trello.com/c/nsZlyil8/1001-afegir-a-filtre-personalitzat-de-contractes-ba-el-camp-prov%C3%ADncia

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