Only include visible fields in views and link row modals

As requested in the community (https://community.baserow.io/t/restrict-requested-field-in-link-to-table-modal/10443), all views can load much faster if we include only the fields visible in the view.

The downside is that the page must reload with the missing fields whenever the user wants to view a field that was previously hidden, but this seems reasonable given the performance gains in all other cases.

We could even load all fields for the current page only the first time a user changes a field’s visibility from hidden to visible, so subsequent similar operations on the same page won’t need to fetch data again from the backend.

Note: We’ll likely need to track which fields are buffered and which aren’t, but views with many linked items could benefit significantly from this feature in terms of load times and overall UX.

This will also affect search: right now we return rows that match the search term in hidden fields. I believe we should only search visible fields, so this change could address that as well, but it’s worth noting it as it might complicates things a bit.