The 'in' rule currently behaves the same way that 'eq' does when used
with multi-selects, which is not correct. It should be modelled by
checking whether the selected values are a subset of the rule values
(i.e. selected values are 'in' the rule values). This patch implements
that for core form rules as well as for the admin settings show/hide.
Several behat features are updated as well, because these were verifying
the incorrect behaviour for multi-select in rules.
Jake Dallimore
d54a04197a