Added `CHECK_CONTAINS` and `CHECK_NOT_CONTAINS` macros.
Added `CHECK_CONTAINS` and `CHECK_NOT_CONTAINS` macros.

Added a simple `CHECK_CONTAINS` and `CHECK_NOT_CONTAINS` to replace
checks of the form `CHECK(foo.contains(bar))`. These macros format
the value of the key in their failure message to assist debugging.

Review: https://reviews.apache.org/r/70661/

kaysoky/mesos,gsantovena/mesos,chhsia0/mesos,chhsia0/mesos,dforsyth/mesos,gsantovena/mesos,kaysoky/mesos,abudnik/mesos,abudnik/mesos,Gilbert88/mesos,dforsyth/mesos,chhsia0/mesos,abudnik/mesos,reneploetz/mesos,kaysoky/mesos,gsantovena/mesos,chhsia0/mesos,dforsyth/mesos,kaysoky/mesos,reneploetz/mesos,gsantovena/mesos,reneploetz/mesos,chhsia0/mesos,kaysoky/mesos,kaysoky/mesos,chhsia0/mesos,gsantovena/mesos,Gilbert88/mesos,abudnik/mesos,Gilbert88/mesos,dforsyth/mesos,Gilbert88/mesos,dforsyth/mesos,Gilbert88/mesos,abudnik/mesos,reneploetz/mesos,abudnik/mesos,chhsia0/mesos,dforsyth/mesos,abudnik/mesos,dforsyth/mesos,gsantovena/mesos,Gilbert88/mesos,reneploetz/mesos,gsantovena/mesos,kaysoky/mesos,Gilbert88/mesos,reneploetz/mesos,reneploetz/mesos