[FEAT] Add grounding, modifiers to parameters after stratification

[liunelson]

Does it make sense to add "grounding" and "modifiers" metadata to the parameters after a model is stratified?

Akin to how state variables:

The above screenshots show a SEIRHD model that was stratified with key = 'location' and strata = <name list of US states and territories> and the modifiers were mapped from the name to the geonames curie.

The goal is to retain/store stratification metadata and permit richer, map-based visualizations of the parameters, beyond the current matrix or table view.

The full example AMR is here:
https://github.com/liunelson/mira/blob/nliu/experiment/notebooks/nliu/data/example_models/model_seirhd_travel_stateCurie.json