feat: restructure to allow usage in other mode projects

[123FLO321]

• move code from app.ts into RadiusServer.ts
• replace logging with a logger specified via the RadiusServer options
• export RadiusServer and associated types

This allows this module to be used in other node projects:

   public async onModuleInit(): Promise<void> {
        if (this.secret && this.tlsOptions) {
            const radiusServer = new RadiusServer({
                logger: this.logger,
                secret: this.secret,
                port: this.port,
                address: this.hostname,
                tlsOptions: this.tlsOptions,
                authentication: this
            });
            await radiusServer.start();
        } else {
            this.logger.log("Not Starting Radius Server because RADIUS_SECRET is not set");
        }
    }

[123FLO321]

Side note: this package.json indicates GPLv3 as license but the repo doesn’t actually include any licenses.
Can we add one?

[simllll]

Looks clean to me :) thanks, i will do one finale check before approving regarding the cli command, but if this works, then its good to go :) thanks for refactoring

[simllll]

Thanks for your contribution!

[simllll]

releassed as major 2.x release, but I also converted it to an ESM package.