Generic/CyclomaticComplexity: add metrics

[jrfnl]

Is your feature request related to a problem?

PHPCS can provide statistics about a code base via the --report=info feature.

This information is recorded by sniffs via the File::recordMetric() method.

I believe it could be interesting for code base owners already using PHPCS to have a straight forward way to get insight into the cyclomatic complexity across their codebase.

Describe the solution you'd like

For the sniff to start recording metrics, probably grouped in a few "steps", possibly along the lines of those mentioned in this comment (+ some more for very high complexity).

Maybe a grouping like this ?

• 1-5 (low risk)
• 6-10 (normal risk)
• 11-20 (moderate risk)
• 21-50 (high risk)
• 51-100 (very high risk)
• 101-500 (very high risk)
• 501-1000 (very high risk)
• 1001-5000 (very high risk)
• 5001-10000 (very high risk)
• 10000+ (very high risk)

• I have read the Contribution Guidelines and this is not a support question.
• I intend to create a pull request to implement this feature.