Add a Secrets git module

[PartMan7]

Goal:

• Have integrated CI/CD for 'secret' components of the repo, hosted in a Git submodule a. Hidden/secret commands (eg: sensitive staff-only commands, or commands for secret rooms) b. Secret implementations (eg: tournament point algorithms) c. Secret values (eg: access codes for internal use that would otherwise clog up .env) (prefer this in cases where the code should be able to function with any value of the variable)

Eg:

// Secret algorithm
function fallback (board: Board): Record<string, number[]>;
Secrets.get('leaderboard_algorithm', fallback);

// Secret value
if (query.params.puzzleId === Secrets.get('puzzle_id', 'catastropika'));

as well as registering all commands under Secrets.getCommands();

[PartMan7]

get<T>(label: string, fallback: T): T { ... }