Update: support class fields in the complexity rule (refs #14857)

[mdjermanovic]

Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request? (put an "X" next to an item)

[ ] Documentation update
[ ] Bug fix (template)
[ ] New rule (template)
[x] Changes an existing rule (template)
[ ] Add autofixing to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:

refs #14857, fixes #14591 (comment)

What changes did you make? (Give an overview)

Update the complexity rule to supports class fields, in a way that the rule now treats them as functions:

• Code in class field initializers doesn't contribute to the complexity of the enclosing code (this is a bug fix).
• Code in class field initializers itself is checked and reported if its complexity is above the threshold (this is an enhancement).

Is there anything you'd like reviewers to focus on?

• Does everyone agree that it makes sense to report initializers?
• Initializers are reported as just "Class field initializer", without referring to the property name. We could add a utility function similar to getFunctionNameWithKind later as an enhancement.

[mdjermanovic]

I believe this can be done better with onCodePathStart()/onCodePathEnd(), so I'll try to refactor the code after we merge #14886.

It's also quite possible that the rule could be entirely refactored to use only the code path analysis info when calculating the complexity as well, but that would require extensive testing.

[mdjermanovic]

Updated the code to use the new code path analysis, and I think this looks better now.

[nzakas]

Does everyone agree that it makes sense to report initializers?

Agree

[nzakas]

LGTM. I think adding the class field name would be a great enhancement but not necessary for this first pass.

[nzakas]

This came in handy! 🎉

[mdjermanovic]

Very! This could have been done in other ways, but it wouldn't look as nice and simple - it would be always difficult to trace what's happening when the initializer is a function.

[mdjermanovic]

closing-reopening to see if that will fix the EasyCLA check.

[mdjermanovic]

All checks are green now, so merging.