Support autocorrection for Lint/SafeNavigationWithEmpty

[koic]

This PR supports autocorrection for Lint/SafeNavigationWithEmpty.

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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.

[bbatsov]

Hmm, that's a weird cop - why don't we check for all predicate methods? Seems to me they all suffer from the same problem.

[bbatsov]

I'm fine with the PR, but I think this cop should be extended to cover all predicates, so it would be more useful.

[koic]

I was late in replying 💦 This cop can be extended, it will be opened as another PR apart from this PR.