n-api: napi_is_construct_call->napi_get_new_target

Remove napi_is_construct_call and introduce napi_get_new_target.

PR-URL: https://github.com/nodejs/node/pull/14698


Reviewed-By: Jason Ginchereau <jasongin@microsoft.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Kyle Farnung <kfarnung@microsoft.com>