Add a warngin when unsupported node.js version is used

[mStirner]

Due to some options/incompatibilities with older node versions e.g. #470 there should be a warning on startup.

There is already a node.js version specified in package.json which can be used to compare to:

backend/package.json

Lines 25 to 27 in 500f0b8

	"engines": {
	"node": ">=0.16.0"
	},