Fix unreported issue that new-style dialog using GimpProcedureDialog
does not display progress.
Change progress reporting to use app's status bar, for all scripts,
old and new style.
As before, report progress whenever a script calls a PDB procedure,
by putting the procedure name in the status bar.
Eliminate progress bar widget from old-style script dialog.
Since it was failing on Wayland, and since it is inconsitent
with new style dialog using GimpProcedureDialog.
