Add verbose output when a ssl error occurs

[lepapareil]

Using hurl to call an https server whose certificates had expired I found that the error output was not accurate enough, example:

test.hurl: failure
error: Http Connection
   --> test.hurl:16:5
    |
 16 | GET https://localhost/test
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ SSL certificate problem

It would be interesting to have the complete error stack allowing us to understand that it was the cause of a certificate expiry in first reading.

[fabricereix]

implemented in #148