quic: Add mechanism similar to waitUntilAvailable to create(Bi|Uni)directionalStream

The webtransport W3 spec allows to pass the option waitUntilAvailable to functions creating streams,
see e,g, here for a bidi stream:

https://www.w3.org/TR/webtransport/#dom-webtransport-createbidirectionalstream

The idea is that if the stream number flow control is exhausted, you have the option for waitUntilAvailable, which if it is set to false throw and tells the caller, that the flow control window for streams is exhausted.

(Alternatively, we can also supply a property to query the current budget).

The same is true for unidirectional stream.

@jasnell @pimterry
What would you think is a good api for this?
P.S: After the stream and session data flow control handling got attention. I will probably after this is decided, activate my stream number flow control tests on webtransport. As the stream number flow control is a another playing field that can easily lead to stalls. (Though I do not know if something is wrong.....)

Start with the WebTransport specification linked in the issue and the existing createBidirectionalStream and createUnidirectionalStream entry points. Compare the proposed waitUntilAvailable behavior with current stream-number flow-control handling and the alternative budget-query idea. Done requires an agreed API for both stream directions and tests covering exhausted and available flow-control windows.