check indentation of braces in namespace decls,
and the comments that often appear with them.
This is my penance for messing up the indentation with
clang-tidy-modernize-namespaces.
As such I have limited it to new-style namespaces for now,
and the check is off by default.
Change-Id: I4db7f10a81c79bc0eece8f8e3ee564da8bc7f168
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/87723
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
84b396a235