Evaluate official PHP SDK

Problem/Motivation

It was recently announced that symfony will be developing the official SDK.

While this module works great (I've used it to test some ideas and it worked great [thank you]) and the SDK is not officially released, I wonder if it makes sense to explore using the symfony version, given that it would be of a broader usage.

Proposed resolution

If you are interested but don't have bandwidth, I can explore and submit an MR.

API changes

Change internal logic to reuse the official SDK.