refactor: Convert RESM to NESM

[kriskowal]

This change is predicated on Agoric/agoric-sdk#3686 and will break any deployment of agoric-cli until it update to a release with the fix.

This change is submited for review of the nesm branch and not recommended to land until telemetry (what telemetry!?) indicates clients have generally upgraded.

Until then, it will be possible to create new dapps with Node.js ESM with the command agoric init --dapp-branch nesm.

[katelynsills]

These changes all look great. I'll leave it to your judgment as to when to merge this in so that it's minimally disruptive.

Given that the agoric-sdk branch mentioned in the PR body got merged, what are the dangers still outstanding?

[kriskowal]

@katelynsills I wrote up a problem description here Agoric/agoric-sdk#3705

The danger of merging this into HEAD is that existing installations of agoric-cli use git clone dapp-fungible-faucet to scaffold, and the same agoric-cli will not be able to run the new NESM deploy script. The issue disappears when all developers update agoric-cli. This will happen for every breaking change.

We can set ourselves up for graceful migration in the future by encoding a tag or branch name in the DEFAULT_TEMPLATE_BRANCH constant in agoric-cli. Then, we would be able to land to HEAD of dapp-fungible-faucet without breaking anything.

We can avoid breaking existing installations by changing the default branch name.

And, we don’t have to do both measures. One solves forward compatibility, the other backward compatibility. I’m sure we could hold advise all developers to upgrade, wait some reasonable amount of time, then land this change, avoiding most of the turmoil for our devs.

[katelynsills]

@katelynsills I wrote up a problem description here Agoric/agoric-sdk#3705

Excellent, thanks. Will take a look