Add .nvmrc file to ensure consistency of Node versions across Layer5 repositories

[M-DEV-1]

Currently, Layer5 repositories do not have a .nvmrc file (meshery/meshery has it), which helps enforce a consistent Node.js version for contributors. While Node.js versions are generally backward compatible, specifying a version helps:

1. Prevent unexpected build or dependency issues due to version mismatches.

2. Ensure security updates by standardizing on a maintained Node.js version.

3. Improve developer experience by reducing environment inconsistencies.

Adding a .nvmrc file with the recommended Node.js version would be a small but valuable improvement.

Expected Behavior

Repositories should contain a .nvmrc file specifying the preferred Node.js version, ensuring consistency across development and deployment environments.

[M-DEV-1]

@vishalvivekm @sudhanshutech

[leecalcote]

Thanks, @M-DEV-1!

[M-DEV-1]

Thanks, @M-DEV-1!

Thank you for assigning this issue to me. I will work on this and submit a PR.