Fixed #3588 to use darwin-x64 for all node < 16.0.0

[Rahulbeniwal26119]

This PR addresses the issue raised by #3588

• For Node Version < 16.0.0 there are no amd64 binaries
• Due to Resotta 2, x64 binaries can be run on new Macs
• Existing logic was having an issue for node versions like 14.18.0, it looked for darwin-amd64 binaries
• This PR updates the existing logic to make a stricter check for all versions less than 16.0.0
• Added a few unit test cases to ensure that changes are behaving as expected.

> bash -c "source ./nvm.sh && nvm install 14.18.0"
Downloading and installing node v14.18.0...
Downloading https://nodejs.org/dist/v14.18.0/node-v14.18.0-darwin-x64.tar.xz...
######################################################################### 100.0%
Computing checksum with sha256sum
Checksums matched!
Now using node v14.18.0 (npm v6.14.15)
> uname -a 
Darwin Mac.lan 24.6.0 Darwin Kernel Version 24.6.0