Imported from the javascript documentation:

- https://socket.io/docs/v3/emitting-events/
- https://socket.io/docs/v3/listening-to-events/

Adapted from:

- https://socket.io/docs/v3/client-initialization/
- https://socket.io/docs/v3/client-socket-instance/

There is no breaking change at the protocol level.

Reference: https://socket.io/blog/socket-io-4-release/

The URL constructor does not support the ws:// scheme, and would throw:

> java.net.MalformedURLException: unknown protocol: ws

Related:

- #650
- #555
- #233

Note: we cannot update the `IO.socket(uri: string)` method without
doing a breaking change.

- replace explicit types by <>
- remove unnecessary interface modifiers

Before this commit, an event sent in the "connect" handler could be
sent before the events that were buffered while disconnected.

Related: socketio/socket.io-client#1458

This commit should prevent some NPE issues encountered after the
parsing of the packet.

Related:

- #642
- #609
- #505

See also: socketio/socket.io-client@53c7374