twister: add search ZTEST_SUITE, ZTEST and ZTEST_F

New ztest API is available in those places:
subsys/testsuite/ztest/src/ztest_new.c
subsys/testsuite/ztest/include/ztest_test_new.h

This requires also changes in Twister code during parsing c files to
find properly test suites and testcases.

Signed-off-by: Piotr Golyzniak <piotr.golyzniak@nordicsemi.no>