fdo#69613:Fix for TOC field flag 'b' should preserved after RT.

(This is partial fix for this bug)

Implementation :
 Provided import & export support for TOC field flag '\b'.

XML file difference :
Before :
<w:instrText>
 TOC
</w:instrText>

After :
<w:instrText>
 TOC \b "bookmark111" \o "1-9" \o "1-9" \h
</w:instrText>

Conflicts:
	sw/inc/tox.hxx
	sw/inc/unomap.hxx
	sw/inc/unoprnms.hxx
	sw/source/core/unocore/unomap.cxx
	sw/source/filter/ww8/ww8atr.cxx
	writerfilter/source/dmapper/DomainMapper_Impl.cxx
	writerfilter/source/dmapper/PropertyIds.cxx
	writerfilter/source/dmapper/PropertyIds.hxx
Reviewed on:
	https://gerrit.libreoffice.org/7256

Change-Id: I194ba95ca8f25234c0d2a14570fd47eac518b9c5