Migrated tests to react-testing-library for the following components:

- Root
- BrowserBar
- BrowserCog
- BrowserCogList
- BrowserImage
- BrowserLocationIndicator

Also, changed `addListener` and `removeListener` on MediaQueryList to `addEventListener`
and `removeEventListener`. `addListener` and `removeListener` are deprecated, and typescript
gets upset about them. The most problematic browser in this respect is Safari;
but it added addEventListener and removeEventListener in version 14.