Use a permissions matrix for npm packages tests

Summary

Follow up of !46867 (merged)

The NPM packages spec has examples depending on these conditions:

• The user role: anonymous, developer, reporter, guest, maintainer
• The project visibility: public, private, internal

Each combination is done in a dedicated context which makes the whole test suite hard to read.

Improvements

• Use table based specs to have a better overview and test thoroughly all the possible combinations.

Risks

• None these changes are on the test side.

Involved components

• npm_X_packages_spec.rb