Support one-line pattern matching syntax

[koic]

This PR supports one-line pattern matching syntax for Layout/SpaceAroundKeyword and Layout/SpaceAroundOperators.

match-pattern node changes differently in Ruby 2.7 and Ruby 3.0.

Ruby 2.7 (Parser::Ruby27)

% ruby-parse -e '42 in foo'
(match-pattern
  (int 42)
  (match-var :foo))

Ruby 3.0 (Parser::Ruby30)

% ruby-parse -e '42 => foo'
(match-pattern
  (int 42)
  (match-var :foo))

And one-line in syntax that represents one-line pattern maching changes
from match-pattern node to match-pattern-p in Ruby 3.0.

% ruby-parse -e '42 in foo'
(match-pattern-p
(int 42)
  (match-var :foo))

---

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.

[bbatsov]

Thanks!