Currently, Layout/SpaceAroundKeyword will allow both of these examples:

return(foo + bar)
return (foo + bar)

This PR changes the cop to always require a space before the opening parenthesis.

Style with space is much more frequent than the style without space, so I'd like to make that explicit in the cop.

Arguments for this change:

• will enforce a consistent style
• is already a much more common style than the no-space style (shown above)
  • also in Ruby org (with space examples, without space examples)
• when closing parens isn't the end of the return expression, no-space style looks weird (e.g. return (foo + bar) * baz vs return(foo + bar) * baz)

Before submitting the PR make sure the following are checked:

• 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).
• Feature branch is up-to-date with master (if not - rebase it).
• 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.