[bug] Accessibility Improvements

* Page size select needs an `aria-label` attribute.
* Filter inputs need an `aria-label` attribute.
* Page nav buttons need an `aria-label` attribute.
* Filter operator icons need `aria-label`
* Allow header to be navigated via keyboard
* Allow sort and reorder actions to be performed via keyboard
* Header options can be triggered via space or enter
* Add/remove column menu keyboard accessibility
