Add landmarks (#564)

Use HTML semantic elements to set the landmarks of the page.

This is helpful for assistive technologies to determine the different regions of content. In our case it's useful for jumping between the different islands that we use to group the form controls.

src/components/LockIcon.tsx

@@ -51,6 +51,7 @@ export function LockIcon(props: LockIconProps) {
         id={props.id}
         onChange={props.onChange}
         checked={props.checked}
+        aria-label={props.title}
       />
       <div className="ToolIcon__icon">
         {props.checked ? ICONS.CHECKED : ICONS.UNCHECKED}