Add a new command: check. This allows users to perform policy checks on
the Attestation result.
The host-key hashes, and the user-data can be tested for certain values.
While at it fix some typos and enable CSV parsing for the Additional-data flags.
Example:
```
pvattest check attestresp checkresult -k hkd0.crt,hkd1.crt
--host-key-check AttKeyCheck
```
Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
Steffen Eiden