Add support for passing a list to filters in list_measurements

[hynnot]

This PR is about the issue #795

Steps:

• Changes to accept the following filters as lists (domain, test_name, probe_cc, probe_asn)

Notes:

• Fix a problem with scores type.
• Fix a problem with the input variable.

[hellais]

Looks good to me. I think you can merge it when the issue with one of the tests is addressed.

[hellais]

We realised in debugging this with @hynnot that input is none in the result listing:

             {'anomaly': False,
              'confirmed': False,
              'failure': False,
              'input': None,
              'measurement_start_time': '2021-07-09T19:14:20.000000Z',
              'measurement_uid': '20210709191422.444165_IT_webconnectivity_21a07ef7982fec55',

Which makes it not possible to test effectively the domain filtering. We should first investigate why it's None and then fix the domain filtering test.

[hellais]

LGTM