Add Mantle as a dependency to MobileFrontend

Updates jobs:

mwext-MobileFrontend-qunit
mwext-MobileFrontend-qunit-mobile
mwext-MobileFrontend-testextensions-master
mwext-ZeroBanner-testextensions-master
mwext-ZeroPortal-testextensions-master
mwext-ZeroRatedMobileAccess-testextensions-master
mwext-browsertests-CirrusSearch-phantomjs

Bug: 67752
Change-Id: I6fcf8a8eb47d0554d3c85348b83b3adf1e0f4f55