Proof of concept: Test react-parallel/PSR-15-adapter

[kpicaza]

This package seems the solution to allow running synchronous PSR-15 middleware in an async non-blocking way.
@WyriHaximus blogged about that yesterday https://blog.wyrihaximus.net/2020/09/next-gen-react-http-psr-15-adapter/

[WyriHaximus]

@kpicaza Am I assuming correctly that you are aware of the PHP ZTS and ext-parallel requirements?