Include implicit rights in UserIsEveryoneAllowed

Return true for UserIsEveryoneAllowed, if the right is included in
the implicit (hidden) grants, since all consumers will include these.

Not allowing read in UserIsEveryoneAllowed hook will have serious
performance impact on the wiki.

Bug: 56975
Change-Id: If4ff036f88fe822ee79672a04ca9dd90788deea4