[Fix #8782] Mark any condition with defined? as an unsafe autocorrection if it is not parenthesized

[dvandersluis]

Previously, the check for defined? in unsafe_autocorrect? only applied when the argument was a single send node with no receiver, but that meant that most times defined? was used in a ternary wrapped in parens, it would be autocorrected incorrectly (since defined? would then be called on the entire ternary instead of the argument). This change makes unsafe_autocorrect? return true if there is any defined? call without parentheses.

Fixes #8782.

---

Before submitting the PR make sure the following are checked:

• Wrote good commit messages.
• Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Added an entry to the Changelog if the new code introduces user-observable changes. See changelog entry format.
• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Run bundle exec rake default. It executes all tests and RuboCop for itself, and generates the documentation.

[dvandersluis]

@marcandre @bbatsov would you be able to take a look at this one too?

[bbatsov]

Appart from my small remark the changes look good. Sorry about the slow response!

[dvandersluis]

@bbatsov no worries, updated with your requested changes now!

[marcandre]

Thanks!