Add open_tab and vat to subscription.request tree view

CHANGELOG:

### ADDED
- [#797](https://gitlab.com/coopdevs/odoo-somconnexio/-/merge_requests/797) Add open_tab and vat to subscription.request tree view

Related card: https://trello.com/c/GQhvebzR/1255-afegir-columna-dni-cif-i-licona-de-lull-open-tab-a-gesti%C3%B3-societ%C3%A0ria

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