UserStatusSelector: set focusPolicy on accept button

UserStatusSelector: set focusPolicy on accept button

otherwise the status text won't be set on macOS as the text box never
loses its focus

`Qt.StrongFocus` is the default focusPolicy on all platforms except for
macOS, there it's `Qt.TabFocus`

the other buttons of the UserStatusSelector don't need that focusPolicy
as they do not modify the model from values in the view

see also:
- https://bugreports.qt.io/browse/QTBUG-110295
- https://codebrowser.dev/qt6/qtdeclarative/src/quicktemplates/qquickabstractbutton.cpp.html#_ZN27QQuickAbstractButtonPrivate4initEv

Signed-off-by: Jyrki Gadinger <nilsding@nilsding.org>