Migrate to Node 14 + 16 and npm 7 + 8

What's Changed

• Update to npm 7 by @ivomurrell in #173
• CPP-576 Use renovate-config-next-beta in Platforms Owned repos by @emortong in #179
• CPP-642 migrate from circleci/* to cimg/* by @serena97 in #184
• Add npm-publish-token CircleCI context by @serena97 in #189
• Add support for Node 14 and Node 16 by @ivomurrell in #188

Breaking Changes

• Dropped support for Node 12

New Contributors

• @serena97 made their first contribution in #184

Full Changelog: v3.1.0...v4.0.0