Permit scrollable AWT tab pages a la scrolled Dialog
UNO dialogs since LibreOffice 4.0 permitted setting HScroll /
VScroll properties to enable scrolling for too large a content.
Conceptually clone this code over to TabPage as well, and register
necessary UNO properties in the toolkit UNO wrappers.
Add missing API documentation also to UnoControlDialogModel,
plus the new properties to the UnoControlTabPageModel
Layout code really doesn't like any extra controls it didn't create
itself - so create scrollbars only on demand.
Change-Id: I67894597ac104320e67ad7989ebf9a7955d99103
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/105573
Tested-by: Jenkins
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>