Migrate Magento PHMD ruleset

[fooman]

Rule

Same rules as https://github.com/magento/magento2/blob/2.3.4/dev/tests/static/testsuite/Magento/Test/Php/_files/phpmd/ruleset.xml

Reason

Running phpmd without requiring a full installation of Magento makes it easier to run the mess detection in isolation

Implementation

Provide a copy of the Magento phpmd ruleset in this repository

[ihor-sviziev]

I believe it could be done as separate ruleset, not Magento2, so it will not affect all people