Add Feature flag for language-directory

[loyaltypollution]

Simple proof-of-concept for adding additional languages via a language-directory.

• Wrote as feature flag to avoid breaking changes.

To-Do?

• Add UI support to allow users to view language directory URLs in frontend.

Questions:

• Is SourceAcademy planning to make conductors a “first-class” concept?
  • removing the hardcoding of languages in drop down?
  • ensuring that all -slang variants support conductors?

Happy to collaborate with relevant people on making conductors first-class if that’s the direction we are taking 👍

[martin-henz]

Yes, the Source Academy frontends should be configurable to provide a desired set of languages and their implementations. The purpose of the language directory is to provide a mapping from language names to the "official" x-slang implementations.

What remains to be worked out is to configure what languages should be provided by sourceacademy.org and sourceacademy.nus.edu.sg and other frontends.

Should that be done in a config file at build time, or should this also come from a github page?

Any proposals?