New features since the prototype:

• time-scoped configs, where the correct config will be selected based on the timestamp of the contribution

• operator keys, allowing plugin creators to create variable operators in their expressions that can be filled in by user configuration. Imagine letting a user choose between applying ADD and AVERAGE to a set of emoji reactions in discord.

• shares config, allowing the user to configure weights for different kinds of participation (for example, author vs mentioned)

• AVERAGE and FIRST operators

This is a... large PR... that adds a few things:

• Discord plugin implementation for CredEquate

• Contributions CLI/API, which is the equivalent of credrank's Graph CLI/API

• Stubs the new Plugin interface methods for all plugins and their declarations

• This builds on #3273 and after this, the last step will be to implement the CredEquate CLI/API.

This adds the credequate API/CLI, which is the credequate equivalent of the credrank API/CLI.

• This CLI turns plugin contributions into scored contributions, creates a CredGrainView, writes the results, and outputs top cred earners to the console