Autocomplete violates hooks rules

[rsimon]

The Autocomplete dropdown (used in the tag widget as well as the comment widet when purposes are enabled) violates the rules of React hooks: it uses useCombobox inside a class component. Interestingly, this doesn't seem to bother Preact at all, but fails when importing RecogitoJS/Annotorious from source into your own React project.

More generally, the Downshift Autocomplete is horrible + has a large memory footprint. In the long run, it would be better to simply kick it out and replace with a hand-rolled solution that does exactly what we need, and not more.