Define relationships between event and footprint sets

[fl-ndaq]

Issue Description

Footprint files are often tied to event set options, and it would be good if this relationship/dependency was represented in the model settings file in some way, similar to the existing relationship/dependency that can be set between event sets and occurrence files (see OasisLMF/OasisLMF#662 for reference).

[benhayes21]

I think this is done

https://github.com/OasisLMF/ODS_Tools/blob/main/ods_tools/data/model_settings_schema.json#L136-L143

closing for now - but let me know if this isn't what you meant @fl-ndaq