Fix Rails/CompactBlank bug when offense is found in block

[r7kamura]

I ran autocorrection of Rails/CompactBlank to my code and confirmed that the code is converted as follows:

-hash.transform_values { |value| value.reject(&:blank?) }
+hash.transform_values { |value| value.compact_blank

It appears that the offense range is incorrect.

hash.transform_values { |value| value.reject(&:blank?) }
                                      ^^^^^^^^^^^^^^^^^^ Use `compact_blank` instead.

Both the .reject call within a block and the .reject call with a block have a block node in the parent, so I think it's not sufficient to simply check whether the parent is a block_type?.

$ cat example.rb 
a { b.reject(&:blank?) }

c.reject! { |d| d.blank? }
$ ruby-parse example.rb 
(begin
  (block
    (send nil :a)
    (args)
    (send
      (send nil :b) :reject
      (block-pass
        (sym :blank?))))
  (block
    (send
      (send nil :c) :reject!)
    (args
      (procarg0
        (arg :d)))
    (send
      (lvar :d) :blank?)))

---

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• Wrote good commit messages.
• Commit message starts with [Fix #issue-number] (if the related issue exists).
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• Squashed related commits together.
• Added tests.
• Ran bundle exec rake default. It executes all tests and runs RuboCop on its own code.
• Added an entry (file) to the changelog folder named {change_type}_{change_description}.md if the new code introduces user-observable changes. See changelog entry format for details.
• If this is a new cop, consider making a corresponding update to the Rails Style Guide.

[koic]

Thanks!