Test: Gather test execution code in app_broker

This change consolidates all code for tests execution into a single
module named app_broker. The broker creates execution environment for
tests (regression and PSA aPI) requireing the tests implement only
entry functoin: void test_app(void *arg) defined in test_app.h

Signed-off-by: Anton Komlev <anton.komlev@arm.com>
Change-Id: I410f6dd0a635b4b543a25af528195d9365dcf320
72 files changed