Add NodeJS version check to cap max version of NR installed

The 2.x branch of the agent supports running on NodeJS 14. This also implies a cap for NR 3.1.x - as NR 4.x doesn't support NodeJS 14.

However, the default snapshot installed when the device first connects specifies `latest` for the NR version.

The task here is to add a check that caps the maximum NR version based on the NodeJS version.

There are two possible ways of doing this:

1. on the platform - *if* the device agent tells us what Node.JS version its using. Will need to check if that's the case
2. in the agent itself - and if so, that should be backported to the 2.x stream.