This makes the "sentence" drawing area from the spelling
dialog (cui/uiconfig/ui/spellingdialog.ui) show up with
role panel instead of "unknown" in Accerciser when using
the qt6 VCL plugin.
This is the same as with gtk3, where the `TEXT_FRAME` role
is mapped to `ATK_ROLE_PANEL`.
Change-Id: I41133c51c64749ccd808cb675fe647a0daefac33
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/170944
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
Tested-by: Jenkins
