If a complex enough document is loaded into Writer and saved as ODT,
then the content.xml's automatic paragraph styles (P<num>) are
re-ordered on each save, which leads to unnecessary noise.

The actual random order is created during import by the time we convert
direct formatting (e.g. from HTML import) to autostyles, as
StylePoolImpl::maRoot stores autostyles in a map that orders autostyle
parents based on their pointer address.

This has benefits like automatic ordering of item sets and fast
comparison, so don't change that, but extend the svl API to also track
the name of those parents.

This way by the time StylePool::createIterator() would iterate over
those autostyles, it can order the parents by their name, so two
import->export runs will result in the same autostyle ordering.

(This appears to be the only indeterminism in content.xml for a test
HTML input, while meta.xml and settings.xml still changes all the time.)

Change-Id: I1cfcae2c664a5c5c3dee48be733046979c1593ed
Reviewed-on: https://gerrit.libreoffice.org/69469Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins