feat: use EvenEmitter3 for web-sdk

[lukas-reining]

This PR

Fixes an issue where the events node polyfill does not comply to the node:events types.
When trying to use the web OpenFeatureEventEmitter the following error message comes up, describing that the events polyfill's EventEmitter is incompatible to node:events EventEmitter.

✘ [ERROR] TS2416: Property 'eventEmitter' in type 'OpenFeatureEventEmitter' is not assignable to the same property in base type 'GenericEventEmitter<ProviderEmittableEvents, Record<string, unknown>>'.
  Type 'EventEmitter' is not assignable to type 'PlatformEventEmitter'.
    Types of property 'addListener' are incompatible.
      Type '(type: string | number, listener: Listener) => EventEmitter' is not assignable to type '(eventName: string | symbol, listener: (...args: any[]) => void) => PlatformEventEmitter'.
        Types of parameters 'type' and 'eventName' are incompatible.
          Type 'string | symbol' is not assignable to type 'string | number'.
            Type 'symbol' is not assignable to type 'string | number'.

This PR fixes that issue by not using the events anymore and instead using https://www.npmjs.com/package/eventemitter3

cc @toddbaert

Related Issues

Fixes #845

[toddbaert]

@lukas-reining @beeme1mr I pushed a small change to remove @types/events since it's not needed now.

[lukas-reining]

@lukas-reining @beeme1mr I pushed a small change to remove @types/events since it's not needed now.

Ah sure missed that one thanks!