Make protected header mandatory

This means that the common iat-verifier logic always call the protected
header checker in the verifier classes. In case of token compilation it
also includes the protected header returned by the verifier class in
the resulting token.

It is still possible for a verifier to make the protected header
optional by implementing _get_p_header and _parse_p_header accordingly.

Change-Id: Ib802e4e30c4c9d2c85addcb7311ab92da3962b99
Signed-off-by: Mate Toth-Pal <mate.toth-pal@arm.com>
14 files changed