Fix: curly removes necessary braces between if and else (fixes #12928)

[mdjermanovic]

Prerequisites checklist

• I have read the contributing guidelines.
• The team has reached consensus on the changes proposed in this pull request. If not, I understand that the evaluation process will begin with this pull request and won't be merged until the team has reached consensus.

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

[X] Bug fix

Fixes #12928

What changes did you make? (Give an overview)

Implemented a more generic check than the existing requiresBraceOfConsequent, to account for more cases when an if can become associated with an unrelated else.

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

In the following case, the rule will still report 2 errors although only 1 pair of braces can be removed:

/* eslint curly: ["error", "multi"] */

if (a) {
    while (b) { 
        if (c) foo(); 
    }  
} else 
    bar();

Auto-fix will remove the outer braces only. After that, the inner braces will become valid.

User can manually remove either of these. After that, the error for the other braces will disappear.

[nzakas]

LGTM. Thanks for the awesome function comments explaining what they do.