STAC: Add Support for `ids`, `collections` query parameters in STAC search endpoint

[rajadain]

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

Currently the STAC Search API supports bbox, datetime, limit, and offset query parameters:

pygeoapi/pygeoapi/api/stac.py

Lines 342 to 347 in 533eb0a

	for qp in ['bbox', 'datetime', 'limit', 'offset']:
	if qp in request_data:
	if qp == 'bbox' and isinstance(request_data[qp], list):
	request_params[qp] = ','.join(str(b) for b in request_data[qp]) # noqa
	else:
	request_params[qp] = request_data[qp]

To add capabilities of STAC Simple Search, we need to add support for ids and collections parameters. intersects is optional in the spec, and since we already support bbox, that can be deferred for now.

Describe the solution you'd like

Support of ids and collections filters.

Describe alternatives you've considered

This could potentially be filtered on the client side, but that is not ideal.

Additional context

N/A

[rajadain]

I'd love to work on this and contribute a pull request, but wanted to open an issue first and receive any appropriate guidance.