Add tests and fix parameter exploding issue

[hamir-suspect]

This fixes the parameters exploding issue. Now parameters defined as:

parameter(
            :some,
            :query,
            %Schema{
              type: :object,
              oneOf: [
                %Schema{
                  type: :object,
                  properties: %{foo: %Schema{type: :string}, bar: %Schema{type: :string}},
                  required: [:foo]
                },
                %Schema{
                  type: :object,
                  properties: %{foo: %Schema{type: :string}, baz: %Schema{type: :string}},
                  required: [:baz]
                }
              ]
            },
            "Some query parameter ",
            explode: true,
            style: :form,
            required: true
          )

will be properly casted into the :some parameter.
How this works:
the parameters that we fetch for a location can be flat (?foo=x&bar=y) before casting we search for any parameters that should be exploded, if we find any we gather all the properties it can hold.
We add those to the struct (as if it was a deep struct param ?some[foo]=x&some[bar]=y and remove them from the query params. in the end query params struct before casting looks like %{"some" => %{"foo" => "x", "bar" => "y"}} instead of what we started with: %{"foo" => "x", "bar" => "y"}.

The ideal way would be to fix how the location schema is composed but that seems to be quite tricky with current implementation.