loplugin:stringviewparam extend to comparison operators

which means that some call sites have to change to use
unicode string literals i.e. u"foo" instead of "foo"

Change-Id: Ie51c3adf56d343dd1d1710777f9d2a43ee66221c
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/106125
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>