Dynamically generate Aggregations

[jamesfisher-geo]

Is your feature request related to a problem? Please describe.

A recent PR implements dynamically generated Queryables (#351). We can do something similar for Aggregations.

Currently, new aggregations require a change to the API code. We have to add a mapping here

stac-fastapi-elasticsearch-opensearch/stac_fastapi/opensearch/stac_fastapi/opensearch/database_logic.py

Line 356 in 353210d

aggregation_mapping: Dict[str, Dict[str, Any]] = {

and the aggregation here:

stac-fastapi-elasticsearch-opensearch/stac_fastapi/core/stac_fastapi/core/extensions/aggregation.py

Line 77 in 353210d

DEFAULT_AGGREGATIONS = [

Describe the solution you'd like
It would be great to have histogram and total count aggregations available for all properties without configuring that in the code. I think we can follow the same approach from #351