Feat: coop agreement new endpoint

CHANGELOG:

### Feat
- [#1108](https://git.coopdevs.org/coopdevs/som-connexio/odoo-somconnexio/-/merge_requests/1108)

Related card: https://trello.com/c/yWvkQMYV/1707-get-per-recuperar-literals-conveni-cooperatiu

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