Merge topic 'policy-version-env'

33856b1d62 Add CMAKE_POLICY_VERSION_MINIMUM environment variable
04721acc6c Tests: Cover CMAKE_POLICY_VERSION_MINIMUM in initial cache script
729470ff6d Tests: Cover CMAKE_POLICY_VERSION_MINIMUM in script mode
6cd10ffed7 Tests: Cover CMAKE_POLICY_VERSION_MINIMUM as cache entry

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Acked-by: John Parent <john.parent@kitware.com>
Merge-request: !10376