Add clustering criteria to maps

[txau]

Our maps cluster data based on geographical proximity. Some users have reported uses cases where clustering would be based in other criteria.

[txau]

Similar: https://github.com/huridocs/uwazi/issues/1687

[fnocetti]

Let's review this when revamping the indexation. We should also fix the performance around how the clustering is performed right now, likely by leveraging elasticsearch's capabilities.