QA - Add PHP Mess Detector (PHPMD) dependency

documentation:

• https://phpqa.io/projects/phpmd.html
• https://phpmd.org

# install
composer require --dev phpmd/phpmd

# Scan PHP source code
vendor/bin/phpmd <file> <format> <ruleset>[,ruleset]
vendor/bin/phpmd <dir>  text     <ruleset>[,ruleset]
vendor/bin/phpmd src/ html cleancode     > phpmdReport_cleancode.html
vendor/bin/phpmd src/ html codesize      > phpmdReport_codesize.html
vendor/bin/phpmd src/ html controversial > phpmdReport_controversial.html
vendor/bin/phpmd src/ html design        > phpmdReport_design.html
vendor/bin/phpmd src/ html naming        > phpmdReport_naming.html
vendor/bin/phpmd src/ html unusedcode    > phpmdReport_unusedcode.html

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related to #20