add "validation" to check if user has valid npm credentials for package

[FrancescoCioria]

requirements

If user has no credentials or has invalid credentials npm publish throws an error.
We should prevent this (common) error with a new validation check

specs

1. user must be logged in npm whoami
2. logged user must have read-write permission (npm access ls-collaborators ${packageName})

misc

{optional: other useful info}