V18 Major

[otaviojacobi]

Change-type: major

See: https://balena.zulipchat.com/#narrow/stream/345890-balena-io/topic/node-sdk-v18

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Contributor checklist

• [x] Includes tests
• [ ] Includes typings
• [ ] Includes updated documentation
• [ ] Includes updated build output

[thgreasi]

How about a commit message like: BREAKING: Support non-user API keys in auth.isLoggedIn() & whoami()

Ideally the change in the return type of the whoami could be in a separate commit, but I'm fine even w/o that.