Accessibility: Improve TextField and Area

Add password and read only states

Change-Id: I5da2fafc0be8ee451ea754774e8daa8aee2f0dcd
Reviewed-by: Jan Arve Sæther <jan-arve.saether@digia.com>
Accessibility improvements

[ChangeLog][QtQuickControls] Accessibility improved: ComboBox is labeled
properly, check and radio boxes report their state correctly

Change-Id: Ia9fe88f032a627c839bd3ef3aec4e2e6cb4517a7
Reviewed-by: Jan Arve Sæther <jan-arve.saether@digia.com>