Add missing relation types items in schema global variables
Some of these global variables are used, in particular, to control schema
views (web/views/schema.py).
While they are currently not properly documented (see #3360868), their
definition are currently incomplete (e.g. one could reasonably expect to find
``cw_schema`` in ``SYSTEM_RTYPES``).
Closes #3486114.
if 'same_as' in schema:
sync_schema_props_perms('same_as', syncperms=False)
sync_schema_props_perms('Bookmark', syncperms=False)