[Fix #841] Fix an error for Rails/ActionOrder

[koic]

Fixes #841.

This PR fixes an error for Rails/ActionOrder when using unconventional order of multiple actions.

With this change, autocorrection blank line positions are not as expected, so they are left to autocorrection of Layout/EmptyLineBetweenDefs and Layout/EmptyLinesAroundClassBody cops.

This PR aims to fix the error, that it may be a better autocorrection later.

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• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• 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.

[r7kamura]

Just to confirm, you are correct that the rule should be changed to "Actions specified in ExpectedOrder should be defined before actions not specified", right?

I think this is not only a bug fix for the cloberring error, but actually changes the rules for the actions order. I wanted to ask this question because if the ordering rule is changed at the same time as the bug fix, I am not sure what order is ideal for this Cop.
(btw, I personally am in favor of the modified ordering rule)

[koic]

Good point. This is a fix to work the fully autocorrection that crashed on Parser::Source::TreeRewriter detected clobbering and didn't work. But it may seem like an unclear rule change to some users.
The doc says All other methods are ignored., anyway I added your suggested note to the doc to make the rule clearer.