Fixes#1305.
## Summary
Enables the new-to-macOS 11 interface idiom of Mac, which removes any interface scaling and brings more Mac-like UI.
## Screenshots
<img width="350" alt="image" src="https://user-images.githubusercontent.com/74188/115946708-ea115500-a477-11eb-9e42-378e76d6e136.png"><img width="350" alt="image" src="https://user-images.githubusercontent.com/74188/115946711-eed60900-a477-11eb-8591-fd01a3711787.png">
## Link to pull request in Documentation repository
<!-- Pull requests that add, change or remove functionality must have a corresponding pull request in the Companion App Documentation repository (https://github.com/home-assistant/companion.home-assistant). Please add the number of this pull request after the "#" -->
Documentation: home-assistant/companion.home-assistant#
## Any other notes
- Updates Settings on Big Sur to use a toolbar to swap between root-level settings screens.
- Fixes blurry web view, only on Big Sur.
- `UISwitch` as a checkbox looks kind of weird; may need to do some Eureka-level changes to make SwitchRow use the `title` property on `UISwitch` to make it connected so the whole thing is clickable. This gets weird because the font size is larger for this property.
