Added experimental support for `mac-arm64` (Apple Silicon) platform.

Note: Node 14 and 16 only. Binaries are compiled manually by maintainers, as Github Actions does not provide arm64 Macs at the moment. Be aware of the [mandatory code signing requirement](https://developer.apple.com/documentation/macos-release-notes/macos-big-sur-11_0_1-universal-apps-release-notes).

- Bump to Node v16.1.0 (#178)
- Bump to Node v14.17.0 (#186)
- Switch to "node-fetch" and add proxy support (#183) (Fixes: #177, vercel/pkg#1163)
- Don't strip global symbols of macOS binaries (#180) (Fixes: vercel/pkg#1155)