fdo#78663 : The File gets corrupted when saved in LO

Problem Description:
The docx file contains a word art inside a drawing tool.
After RT, nesting of <txbxContent> tag is happening which
is causing the corruption.

Solution: Created a service in util.cxx for checking
few shapetypes for which textbox with content is not
allowed. This check also helps to find that if we are
already inside a DML then we should purely read VML
Information.An existing UT testWordArtWithinDraingtool
was failing. The UT is related to same issue
(word art inside drawing tool) hence changed it
accordingly. Following is the commit id of the
UT-Change-Id: I00e94712e912ad1977fcb65a945fefb927795d77

Change-Id: I7e456c9f6a69af80da443e29eb02a64ba7d59468
Reviewed-on: https://gerrit.libreoffice.org/10229
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>
Tested-by: Luboš Luňák <l.lunak@collabora.com>