Don't start if user has no home directory
Don't start if user has no home directory

If the user doesn't have a defined home dir (env var `HOME`,
`USERPROFILE` or `HOMEPATH`) and the `userDir` is not passed on the
command line then we shouldn't start as we don't know where to copy the
default `settings.js` file to or where to store flows

fixes #3539

node-red/node-red,node-red/node-red,node-red/node-red