tests/eas/acceptance: Add EasTest API
tests/eas/acceptance: Add EasTest API

This adds a class EasTest that inherits from LisaTest to provide a
common set of functions for EAS acceptance tests.

mdigiorgio/lisa,credp/lisa,joelagnel/lisa,bjackman/lisa,mdigiorgio/lisa,ARM-software/lisa,credp/lisa,arnoldlu/lisa,arnoldlu/lisa,credp/lisa,joelagnel/lisa,credp/lisa,bjackman/lisa,ARM-software/lisa,ARM-software/lisa,ARM-software/lisa