Redesign the list items in the People menu.

[Gigabyte5671]

The old design was focused around the volume slider and mute button, requiring an extra click to access the majority of actions. This was a little backwards, clunky, and made the list items super thick:

In the new design the controls take precedence, providing quick access to the majority of actions. The volume slider becomes accessible via a dedicated volume button. The volume button's icon provides an indication of the current volume setting at a glance:

Closes #117.

[Gigabyte5671]

There are a few bugs that need to be fixed before this PR is complete:

• The new volume slider cannot be dragged. ✅ Fixed by commit 074ff56.
• The new volume slider is not accessible on mobile, due to it relying on a mouseenter event. ✅ Fixed by commit 074ff56.
• Names longer than ~15 characters, a menu width of less than ~350px, or a larger font size than default will cause the controls to wrap. This is desired behaviour, but puts us mostly back where we started with "thick" list items. ⏺️ This is not a huge issue. The readability aspect of this is fixed by commit b735ad7.