tdf#130857 qt weld: Support Writer "Watermark" dialog

This means that native Qt widgets are used for that dialog
now when using the qt5 or qt6 VCL plugin and starting LO with
environment variable SAL_VCL_QT_USE_WELDED_WIDGETS=1 set.

The dialog can be triggered using "Format" -> "Watermark"
in Writer.

Change-Id: I37bc11c301675655f9e13595bb56b785f658138f
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/191926
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <[email protected]>
diff --git a/vcl/qt5/QtInstanceBuilder.cxx b/vcl/qt5/QtInstanceBuilder.cxx
index 0a30035..7f760b5 100644
--- a/vcl/qt5/QtInstanceBuilder.cxx
+++ b/vcl/qt5/QtInstanceBuilder.cxx
@@ -174,6 +174,7 @@
        u"modules/swriter/ui/rowheight.ui"_ustr,
        u"modules/swriter/ui/splittable.ui"_ustr,
        u"modules/swriter/ui/testmailsettings.ui"_ustr,
        u"modules/swriter/ui/watermarkdialog.ui"_ustr,
        u"modules/swriter/ui/wordcount.ui"_ustr,
        u"sfx/ui/documentpropertiesdialog.ui"_ustr,
        u"sfx/ui/editdurationdialog.ui"_ustr,