Fix metric_keys as a top-level query parameter

[nachomaiz]

Description

metric_keys in brandscape_data method is not a top level

Motivation and Context

The metric_keys parameter in brandscape_data was not correctly allocated to the top level of the query, and parsed instead as a filter.

This PR adds metric_keys as a parameter of the Query object, to make it work with the Fount API.

Tests have been updated to check whether parameters are being parsed and allocated correctly by the Client endpoint methods.

How Has This Been Tested?

Ran nox tests as well as mypy and pylint.

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added the changelog accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.