Fixing the way aqueduct TestRequest serializes list query parameters

[Reductions]

Up until now list query parameters were serialized in such a way:

url?query=[1, 2]

This is not the way aqueduct expects list parameters to be sent with that pull request the way lists are serialized is:

url?query=1&query=2

[ali-thowfeek]

@Reductions I was trying to write a test like

harness.publicAgent.get("/search", query: {"query": "1", "query": "2"});

But soon realized that it's impossible do that in dart with the map containing duplicate keys.
would this PR fix it? where i would be able to write

harness.publicAgent.get("/search", query: {"query": ["1", "2"]});

[Reductions]

Yes it would. But it would not be merged as the framework is no longer supported. Run away while you have an option.