update to node 16

[mharrigan26]

Overview

Update to NodeJS 16

• change to Node 16 in main.yml for gh workflow
• run npm ci
• add engines property to package.json

Testing recommendations

• unit tests pass
• e2e tests pass

Checklist

• Code is written and works correctly;
• Changes are covered by tests;
• Documentation reflects the changes;
• Update rebar.config.script with the correct tag once a new Fauxton release is made