This patch fixes some accessibility problems on the main settings page.
Most notably, it makes sure that the different options have labels which
are picked up by screen readers.
As a more generic addition, this also makes sure that the dropdown
component will always have a proper label constructed, explaining what
the dropdown is for and what its current value is.
This patch should fix most of the problems for users trying to access
the user settings via screen reader. It makes sure user interface
elements can be reached via keyboard and provides proper labels, roles
and values so you not only can interact with elements but also know what
you are actually changing.
While not focused on other views, this should also already fix a number
of accessibility issues with other settings pages.
