BREAKING CHANGE: rename from FarClass to ExoClass, etc

[erights]

Fixes endojs/endo#1193 .

@dtribble and I were brainstorming name alternatives to FarClass (which we both hate for somewhat different reasons). There are three salient differences from normal object programming, where FarClass only suggests the first and third.

• It is a remotable, meaning it is exposed to messages from outside the vat (hence "Far")
• Related, it is protected by an interfaceGuard that does the first type-like phase of input validation
• It is programmed in a class-like manner, with inline methods in the concise-method syntax, accepting their instance-specific access via their this binding (hence "Class")

We also need to name the instance case, and FarInstance is way too awkward. The instance case has the first two features but not the third.

New aha: "Exo" does double duty.

• As a prefix meaning "outside", it suggests the remotable meaning. That was why I suggested Exo in the first place.
• It lets us introduce the metaphor of the ExoSkeleton without being confused with the exoskeleton itself. "An exo is a creature with an exoskeleton" is a memorable explanation, even if there is no RL noun "Exo".

Also

• It is short, so for the class case "ExoClass" still works.
• It is distinct from our current "Far" and so the "Instance" qualifier isn't needed for the protective instance case.

But this last bullet (distinct from "Far") means that it isn't an answer to our first search for a term, since it doesn't cover remotable objects without a protective exoskeleton (currently, "Far objects" and "remote presences"). Oh well. I think the rename is still worth it.

[kriskowal]

Looks mechanical to me. I’m warming to the idea that this name change is a net improvement and, stew as I have on this question for long enough, have not found a more positive improvement.

[kriskowal]

Caveat: this appears to be a breaking change and I do not know how it affects upgrade. However, the commit message should be framed like:

refactor(ertp)!: Rename etc

*BREAKING CHANGE*: How to update dependencies

This will ensure that Lerna generates a changelog and the appropriate version bumps.

[erights]

See previous discussion at #6118
See table of options at https://docs.google.com/spreadsheets/d/1yhKgzMOfmZOTnvP3Bh4p16H9RyYq_WhOlxZ3Qicx_Oc/edit#gid=0

[gibson042]

I think "Exo" is a big improvement over "Far", and even the isolated noun usage works pretty well.

[erights]

Please look at #6818 for another candidate. I think I like that one better.

[turadg]

Late in the day, I confused this and #6818 and even #6118.

[turadg]

This simple change looks good to me. As I wrote on #6323 (review) I ask that the naming rationale be documented within the codebase. E.g. packages/store/docs/terminology.md.