Auto-import system APIs

[worksofliam]

Changes

• Adds ability to import system APIs that have not yet been defined in the source scope.
• Shows code example for some system APIs
• New @value tag allowing the user to define possible values for parameters, subfields and variables

Checklist

• [ ] have tested my change
• [ ] updated relevant documentation
• [ ] Remove any/all console.logs I added
• [ ] eslint is not complaining
• [ ] have added myself to the contributors' list in the README
• [ ] for feature PRs: PR only includes one feature enhancement.