Sync TopBarItem/TopBarTrigger with UXPin

## Things to Change

- No more bottom border on hover, just a background color change
- Focus state should use the default focus ring instead of bottom border
- Bottom border should only be visible when trigger is active (this could be set via an `active` prop or checking for `aria-current`)
- Font-weight for both Item/Trigger should match (`400`)

Other considerations:

MenuBar should always be aligned to the right when inside of the TopBar component.

See [design system](https://app.uxpin.com/design-system/c933c74928e2195cc540/ui-patterns/213721) for examples of what values to use for the various states. Reach out to @dequelabs/cauldron-design if anything is unclear.

Locate the TopBarItem, TopBarTrigger, and MenuBar components, then compare their current hover, focus, active, font-weight, and alignment behavior with the linked UXPin design system. Done means the requested states and right alignment match the design examples; contact @dequelabs/cauldron-design if any values remain unclear.

Written by the indexing model from the issue text.