Broadcast emits only return a single ack value

Improve type definitions of `emit` and `emitWithAck` to prevent uses in an incorrect manner

This avoids having tons of red squiggles showing on the IDE for a succeeding test
tsd will still error out if a `ts-expect-error` goes unused, so it functionally is about the same

This makes DX nicer as typescript will show errors in the file as you work, instead of requiring compilation steps