add polyfill for `EventEmitter`

[danielroe]

Describe the feature

we still have a hard node dependency for readable/writeable stream via https://github.com/unjs/unenv/blob/main/src/runtime/node/stream/readable.ts, meaning (for example) that createCall and createFetch are only runnable in a node environment at the moment.

Additional information

• [X] Would you be willing to help implement this feature?

[danielroe]

Oops, sorry, missed it: https://github.com/unjs/unenv/blob/main/src/runtime/node/events/index.ts#L11-L12