Remove engines stanza and update package-lock

[pandringa]

To carry over a conversation from Slack - if we remove the engines block do we have any other way of noting the supported Node version? As a developer it would be much more helpful to keep track of which version is required, even if we need to update it every once in a while. (For instance, I think a pending vs-components version might require Node 18 — and we can avoid some debugging pain by either using volta or a note somewhere else.)

I also note that the CircleCI job currently uses 16.13, so I think there's some value in keeping local dev environments synced to that version. If we're concerned about v16 reaching end of its maintenance phase, should we update that too?

[joannaskao]

Closing as superseded by #331