Get rid of 'read_hkd' by refactoring the 'get_verified_hkds' function.
For this a new HkdLoader::load_and_verify is introduced that is a
reworked version of the original code.
In addition, add test cases for testing all the edge cases.
Assisted-by: IBM Bob:1.0.6
Signed-off-by: Marc Hartmayer <marc@linux.ibm.com>
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
