Xsecure direct tests and PC hardening assertion

Created by: silabs-krdosvik

Two comments for this PR:

1. The assertions a_xsecure_pc_hardening_branch_set_alert_major and a_xsecure_pc_hardening_jump_set_alert_major have not converged yet (but have a bound of 36 and has run for almost a day). For now I assume that it fine, so that you at least can review my work. I will update you when they have finally passed or faild.

2. The RTL for PC_hardening = 0 is not yet implemented. This means that the assertions that assumes pc_hardening =0 can be faulty and must be checked when the rtl is implemented.

The assertion passes ci check (except from the debug test). The direct test pass as well.