feat: Print errors when providing unsupported lock files

chore: Move mock-registry to different sub directory

We are going to need a new mock for filesystem stuff as well, in order to have an easier time testing different lock files. So a mocks folder in the root dir makes sense to host registry and mock file systems.

See:

• #16
• #13

feat: Print errors when providing unsupported lock files

We now print errors if any lock file is used, which we cannot parse:

• yarn@2 (or higher) lock files, which we do not support yet
• package-lock.json (npm)
• pnpm-lock.yaml (pnpm)

Additionally we handle parsing faulty yarn files better and finally add tests for the parsing.

chore: Refactor e2e tests to test output as well

Also add test cases for unsupported files. We also make our fixture files a little bit smaller...

chore: Drop node: namespace

In order to support node@15.