Add crypt_dump_json() API call.
Add API call that can directly print JSON metadata area from LUKS2 device.
For commandline it also adds --dump-metadata-area option for luksDump action.
Note that the binary metadata (UUID, version etc) is not part of this output. (We reserve flags parameter to be able to add this later.)
Fixes: #511 (closed)
Edited by Milan Broz