[2.0.0-beta1] Ci add PHPMD job

Let's merge it in beta1

the MR looks nice, could we just add the parameter on phpmd command line to use .phpmd.xml in the project root?
maybe it is already the case, i just wanted to be sure.
thank you :)

I didn't notice the config file, fixed.

many thanks, i merge, that's a super new addition to the pipeline :)