Merge topic 'gtest-property-list-values'

83baea27a1 GoogleTest: Remove the LIST_SEPARATOR option
3748ca9fc7 GoogleTest: generate single discovery script
3fbf8e23fd GoogleTest: Remove `add_command` function

Acked-by: Kitware Robot <kwrobot@kitware.com>
Tested-by: buildbot <buildbot@kitware.com>
Merge-request: !11911