Rather than having a scrollable listbox within a scrollable list of
widgets, move the listbox out to a separate dialogue.
This involves separating out all the code to query the apps, to get and
to set the app filter, from `MctUserControls` out into the new
`MctRestrictApplicationsSelector`. Most of it is unchanged, aside from
its interaction with the filter: the filter is now provided to the
widget by the calling code, rather than being queried by the widget
itself. The widget’s status can be queried into an
`MctAppFilterBuilder`, rather than being used to set the app filter
directly.
This commit redesigns the appearance of the relevant widgets in the main
window so that they follow the new list-box-like visual design. A
following commit will apply similar changes to the other widgest in the
main screen.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
bffab0942f