publish pre-release builds to NPM registry

[turadg]

What is the Problem Being Solved?

Sometimes pending changes are needed by downstream consumers before they're in an Endo release. E.g. #1850

Description of the Design

Build and publish pre-release versions.

agoric-sdk publishes on each commit to master in its dev-canary job. https://www.npmjs.com/package/agoric?activeTab=versions shows the versions ({next-version-number}-dev-{gitSha}).

Publishing nightly would also suffice. That numbering scheme could be {next-version-number}-dev.YYYYMMDD (like TypeScript has).

Security Considerations

n/a

Scaling Considerations

n/a

Test Plan

Trigger the job and confirm the packages are at npmjs.org

Upgrade Considerations

n/a