POC for realtime PHP SDK

[sacOO7]

Task will consist of trying out following PHP execution model and websocket client lib

1. ReactPHP and Pawl client
2. Amphp and amphp websocket client
3. Try texttalk/websocket-client and use PHP threads/fibers

┆Issue is synchronized with this Jira Task by Unito

[jamienewcomb]

to be picked up when timelines on php realtime requirement is confirmed