Improve styling for the review modal and when editing articles/metadata & Make kbox responsive to window resizing and overflow

[denyshon]

Resolves #2190, #3106, #3108. Maybe there are other issues filed?

• Fix the "Needs change" styles in the reviewer modal (kbox).
• Fix margins in the reviewer modal (kbox).
• Style checkboxes in the reviewer modal (kbox) and on the edit_metadata/new_document pages to allign with SUMO UI.
• Style radio input in the reviewer modal (kbox) to allign with SUMO UI.
• Fix font weight in the reviewer modal (kbox) to allign with other modals.
• Normalize text field dimensions in the reviewer modal (kbox) and on the edit/new_document/edit_metadata pages. Only set max-height for the content field, and make all the other fields full-width except for the category selector.
• Kbox: call setPosition() on window resize.
• Kbox: when autopositioning a modal that's higher/wider than the viewport, leave minimal margins at the top and at the left.
• Kbox: handle overflow. When a modal is higher/wider than the viewport, set max-width/max-height for it to fit the viewport (with minimal margins) and allow scrolling.
• In the reviewer modal (kbox), handle overflow after clicking the "Needs change" checkbox.