Instance Page /Browse v2

Stuff we've done in other PRs (worth sanity checking):
- [x] Upload CSV
- [x] Upload JSON
- [x] Export CSV
- [x] Hide and show columns
- [x] Letting the user resize column widths
- [x] UI vs API filtering and sorting toggle (the “only cached” button?)

Future improvements:

- [ ] Event subscription button (the “auto” switch? instead of polling, let's watch for changes)
- [ ] Export JSON (instead of just CSV)
- [ ] Altering schema (cross link to the schema in the Applications tab, if this table is defined by a schema file)
- [ ] Filtering dialog (by existing fields, and building complex queries)
- [ ] Hover over column to show the type, computed, relational properties