Task: check what PHPMD checks and if there are replacement sniffs

[jrfnl]

Via:

• https://yoast.slack.com/archives/CQ2G9ASK1/p1596032760007100
• https://yoast.slack.com/archives/CQ2G9ASK1/p1596032943008700
• https://yoast.slack.com/archives/C0361PEK4/p1592487948161600

Some PHPMD checks used to be run via CodeClimate. Now CodeClimate has been turned off, these are no longer run.

A number of things which PHPMD checked, can (also) be checked via sniffs.

It should be inventoried:

• Which checks in PHPMD were considered useful.
• If there are sniffs available for the same either in PHPCS itself or in external sniff libraries.

From the Slack conversations:

"At some points codeclimate made me think more about my code. Complexity of methods is one of those. Not using else-statement. Maybe we should communicate that kind of principles as much as possible "

[jrfnl]

Blocked as this needs a list of checks which the devs found useful from PHPMD before a search can be done for similar sniffs.

[jrfnl]

List of checks in PHPMD: https://phpmd.org/rules/index.html