Added elimination of maps:is_key/2 calls to HiPE

 * Implemented removal of maps:is_key/2 calls of which the result is
   known in a new pass during the typed phase, called
   hipe_icode_call_elim.
 * Added the option icode_call_elim that enables the
   hipe_icode_call_elim pass, and made it default for o2.
Added a HiPE test suite that tests that optimisations work

 * Added a suite opt_veryfy_SUITE.erl to HiPE that tests for the results
   of optimisations, with a single testcase that checks that the
   icode_call_elim optimisation pass does remove calls to maps:is_key/2
   where sound and not otherwise.
 * Made hipe_testsuite_driver only create explicitly listed suites.