How to forward stream from one mediasoup v3 server to another?

[ibc (Iñaki Baz Castillo)]

Done in mediasoup 3.4.9:

mediasoup 3.4.9 released

Internals: add Utils::Json::IsPositiveInteger() to not rely on is_number_unsigned() of json lib, which is unreliable due to its design. Avoid ES6 export default and always use named export (it does not affect public API). router.pipeToRouter(): Ensure a single PipeTransport pair is created between router1 and router2. Since the operation is async, it may happen that two simultaneous calls to router1.pipeToRouter({ producerId: xxx, router: router2 }) would end up generating two pairs of PipeTr…