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.

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if not rql('CWConstraintType X WHERE X name "RQLUniqueConstraint"',

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           ask_confirm=False):

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    rql('INSERT CWConstraintType X: X name "RQLUniqueConstraint"',

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        ask_confirm=False)