Describe the bug
In working on the PR to add support for voiced captions, I had to add some new preferences. Doing that, I discovered that they are pretty messy, and could use some refactoring.

Major changes proposed:

1. Create prototypes to generate input fields that can be called with the relevant data.
2. Create prototype for preference panels, so it's easier to insert a setting into a specific panel.
3. Work on resolving Multiple instances of preferences modals inserted #658, so that the preference panel is created once and reused. Preferences are already global, so having individual panels is unnecessary.