There are some inconcistencies in the application when it comes to
button UI elements because we're using `StatusButton` in some places,
in other we use `StyledButton`. The latter is the original
component we've created when we started out building Status
Desktop, but is planned to be removed entirely in favour of
`StatusButton`.
This commit replaces the usages of `StyledButton` with `StatusButton`
Necessary cases are:
- Onboarding to show the list of 5 accounts
- In QML when we show it to the user for the backup
- Change it to a Loader, so the component and its memory is cleaned when closed