Consider terminology change from "Contact Event Numbers"

[hdevalence]

As discussed on the cross-organizational Zoom call, we should try to standardize terminology between all the different contact tracing protocols.

One point of discussion was the term "Contact Event Number". Some points of discussion:

• the name should not have "ID" in the name, because this suggests that there's a strong identity, which is not the case;
• the name should have something that indicates that it's a short-lived value;
• "ephemeral" is less clear than "temporary" for non-native English speakers.

A preliminary alternative is "Temporary Contact Number" (TCN)

[zssz]

I like "Temporary Tag" (TT) also.

[hdevalence]

@zssz Would you be happy with "TCN"/"TCK"?

[hdevalence]

Making this change isn't particularly difficult -- it just requires careful search-and-replace -- but it does touch basically every part of the repository, so it will cause any outstanding changes to have conflicts.

For this reason I would like to: 1) definitively decide on new terms, if we decide to change terms at all 2) wait for all in-flight work to land 3) make the change then.

[hdevalence]

Doing this now.