eve/ssh: change hassh logging format

eve/ssh: change hassh logging format

Elastic search didn't accept the 'hassh' and 'hassh.string'. It would
see the first 'hassh' as a string and split the second key into a
object 'hassh' with a string member 'string'. So two different types
for 'hassh', so it rejected it.

This patch mimics the ja3(s) logging by creating a 'hassh' object
with 2 members: 'hash', which holds the md5 representation, and
'string' which holds the string representation.