[PD] improve face selection for Pad/Pocket

- this PR extends PR #7191 as described in this forum thread: https://forum.freecadweb.org/viewtopic.php?f=3&t=70327

src/Mod/PartDesign/Gui/TaskPadParameters.cpp

@@ -104,6 +104,10 @@ void TaskPadParameters::onModeChanged(int index)
         break;
     case Modes::ToFace:
         pcPad->Type.setValue("UpToFace");
+        if (ui->lineFaceName->text().isEmpty()) {
+            ui->buttonFace->setChecked(true);
+            handleLineFaceName(); // sets placeholder text
+        }
         break;
     case Modes::TwoDimensions:
         pcPad->Type.setValue("TwoLengths");