What should we call the EPA CAMD - EIA crosswalk?

[aesharpe]

We're in the process of integrating a crosswalk between EPA CAMD data and EIA data. Right now, we've decided to call it epacems_unitid_eia_plant_crosswalk, but it's more than that.

The only EPA/CAMD data PUDL currently uses is CEMS, so we've been calling the crosswalk the "cems" crosswalk, but this isn't accurate if we ever expand to include more data from CAMD. Also, the crosswalk is really mapping epa units to eia generators and boilers because entire plants aren't always linked to one point source (unit) for emissions.

Given this info, how do people feel about the name?
Here are some other name ideas:

• epacamd_eia_crosswalk
• epa_eia_crosswalk
• camd_eia_crosswalk
• epacamd_unit_eia_bg_assn

[aesharpe]

See this PR thread for the conversation!
#1692