chore: add PhpMetrics

[kenjis]

Description

• add PhpMetrics

How to Use:

$ composer metrics
$ open build/phpmetrics/index.html

Checklist:

• [x] Securely signed commits
• [] Component(s) with PHPDoc blocks, only if necessary or adds value
• [] Unit testing, with >80% coverage
• [] User guide updated
• [] Conforms to style guide