Improve contract API
CHANGELOG:
### Added
- [#1052](https://git.coopdevs.org/coopdevs/som-connexio/odoo-somconnexio/-/merge_requests/1052) Improve contract API:
- Add pagination
- Add more contract info in the response
- Add shared data info
Related card: https://trello.com/c/X4vXtROq/1673-millores-api-de-contractes-paginaci%C3%B3-v2
Include: https://trello.com/c/Hc6KAjN5/1410-contractes-odoo-per-ov-paginaci%C3%B3, https://trello.com/c/w94x7DAl/1660-odoo-api-contracts-v2
Edited by Daniel Palomar