and merge the two existing implementations of the idea - SotMutexHolder
from package and RefCountedMutex from connectivity

Change-Id: I87f09f359ac798cf934381a2c75225dab71dd43e
Reviewed-on: https://gerrit.libreoffice.org/38972Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>