fix: add cc field to auth.pl

[stephanegigandet]

add cc field requested by @monsieurtanuki in openfoodfacts/openfoodfacts-dart#903 (comment)

note that cc can also be "world"

also removed some fields if their value is undef or empty

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud

[alexgarel]

Cool.

[monsieurtanuki]

@stephanegigandet Is it already working in PROD?
I've just got this response, with country but no cc:

{
  "status":1,
  "status_verbose":"user signed-in",
  "user":{
    "admin":0,
    "country":"en:france",
    "moderator":1,
    "name":"(my name)",
    "preferred_language":"fr"
  },
  "user_id":"monsieurtanuki"
}

after a call like that:

    final Uri uri = uriHelper.getPostUri(
      path: '/cgi/auth.pl',
    );
    final Response response = await HttpHelper().doPostRequest(
      uri,
      <String, String>{'body': '1'},
      user,
      uriHelper: uriHelper,
      addCredentialsToBody: true,
    );

[teolemon]

Deployed to .net currently @monsieurtanuki