Sort refinementList values before sending HTTP request (so request caching works as expected)

_Deleting my OP to not cause confusion. See my two posts below for the remaining issue, which is refinement list values should probably be sorted before building HTTP request string._

**Environment:**

- OS: Mac
- Browser: Chrome (Reproduced in Firefox & Safari too)
- Version: `"react-instantsearch-dom": "^6.5.0",`

Trace refinementList values from the widget into the HTTP request-building path, then inspect how the request string is assembled and cached. Confirm the behavior with the existing test suite or a focused reproduction if no relevant test is apparent. Done means equivalent value order produces the same request and allows request caching to work as expected.

Written by the indexing model from the issue text.