Fix: preserve formatting when rules are removed from disable directives

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

refs #14878, fixes #14617 (comment)

This fix aims at preserving the original formatting of eslint-disable-* directives when individual rules are being removed during the autofix.

What changes did you make? (Give an overview)

Extended the removal range for the first and the last element in the rule list.

If the first rule is being removed, the removal range will include all whitespace up to the name of the second rule in the list. This way, used will start at the same position where unused was.

// eslint-disable-line unused , used
                       ^^^^^^^^^

If the last rule is being removed, the removal range will include all whitespace on the left side up to the name of the previous rule in the list. This way, used will end at the same position where unused was ending, relative to the content that comes after.

// eslint-disable-line used , unused -- comment
                           ^^^^^^^^^

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

[nzakas]

Nice job!