XSD 1.0 cos-all-limited: a reference to a model group whose content is an
`all` group is itself an all-group particle, so its maxOccurs must be 1 and
its minOccurs 0 or 1. The direct `<all>` element was already checked by
allGroupLimitedErrors, but a `<group ref>` resolving to an all group was not,
so corpus particlesEa025 (`<group ref="x:G" maxOccurs="2">` to an all group)
was accepted.
Add allGroupReferenceMaxOccursErrors: collect the names of group definitions
whose content is an all group, then flag a group reference to one whose
maxOccurs is not 1 or whose minOccurs is not 0/1. The check runs over a single
schema document tree, where group names are unique, so the by-local-name match
cannot collide; a cross-document reference lives in a separate container and is
under-rejected (never falsely rejected).
XSTS invalid-schemas-accepted 36 -> 35; valid-schemas-rejected held at 0.