The type of the config object.
type OverrideKeyMap = InferOverrideKeyMap<MainEnv & TestEnv>;
// Example usage of OverrideKeyMap, where the keys are the original config keys and the values are the override keys
const env = new EnvConfigLoader<OverrideKeyMap>(undefined, {PORT: 'HTTP_PORT'}); // get PORT value from process.env.HTTP_PORT
Helper infer type to write override keys to config loaders