Add request context when outputing error

[jcamiel]

The current Hurl output when outputting error is to display the source line where the error has happened:

...
foo.hurl: Running [9/12]
error: Assert status code
   --> foo.hurl:78:6
    |
 78 | HTTP 200
    |      ^^^ actual value is <404>
    |

foo.hurl: Failure (5 request(s) in 411 ms)  

It can be difficult to identify the request without reading the source file. To help this, we could print the curent request line:

...
foo.hurl: Running [9/12]
error: Assert status code
   --> foo.hurl:78:6
    |
 73 | GET {{orange_url}}/api/filters
    | ...
 78 | HTTP 200
    |      ^^^ actual value is <404>
    |

foo.hurl: Failure (5 request(s) in 329 ms)

If the error happens on a request line (like timeout, etc... we don't need to change anything