Server Sent Events for functions-js client

[TimNEverett]

The idea it to add a Server Sent Event function added to the FunctionsClient that returns an event source.

I imagine the function call to be something like:

const { data: { eventSource }, error} = supabase.functions.sse('function-name', {
    ...usualFunctionParams,
    onStart: () => {},
    onMessage: (data) => {},
    onError: (error) => {},
    onDone: () => {} 
})

and the returned eventSource would implement eventSource.close() for manually ending the stream.