Proposal: Move WebSocket support into an optional dependency

[simolus3]

On most platforms, the PowerSync JavaScript SDK uses RSocket by default to stream sync data from the PowerSync service. RSocket mostly started out as a workaround for React Native where we couldn't reliably stream HTTP responses in the past. Implementing RSocket is not trivial though, and all our SDKs pay the cost of bundling the fairly complex RSocket client packages.

While RSocket also helps with misconfigured HTTP servers or middleware attempting to buffer the streaming sync response, it's not generally all that useful for most platforms. So, we would like to unbundle it from all JavaScript SDKs except for React Native.

This is a breaking change: If you want to keep using the WebSocket-based connection method, you'd have to add an additional PowerSync dependency to enable that.