Recover Ruby 2.2 code analysis using TargetRubyVersion: 2.2

[koic]

Follow up #10632 (comment).

Reverts part of #6766, #7026, and #7030.

Only the Ruby version (2.2) to runtime should have been dropped, not code analysis.
This PR makes Ruby 2.2 code analysis with TargetRubyVersion: 2.2.
It aims to solve essentially the same problem as #10626, #10632, and #10640.

Previously, there was the following default enforced style when_needed for Style/FrozenStringLiteralComment cop.

# @example EnforcedStyle: when_needed (default)
#   # The `when_needed` style will add the frozen string literal
#   # to files only when the `TargetRubyVersion` is set to 2.3+.
#   # bad
#   module Foo
#     # ...
#   end
#
#   # good
#   # frozen_string_literal: true
#
#   module Foo
#     # ...
#   end

This PR does not restore that option, but sets the minimum_target_ruby_version 2.3 to make always (default) apply by default. It is a simple solution that does not handle frozen literal magic comment added in Ruby 2.3 when TargetRubyVersion is Ruby 2.2 or lower.

---

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]

Not sure if we need to go back so far, as I doubt there are many projects that still target such an old Ruby release. I'll leave this up to you to decide. Personally I was happy when we got back to 2.5. :D

[koic]

I found the following backlink in PR #10632 that recovered Ruby 2.4 code analysis.
brianmario/mysql2#1256

So, there seems to be use case with gems that support older Ruby versions. Perhaps RuboCop's analysis can recover up to Ruby 1.9 code. I'm trying it, but I'm not sure if it's the best 😅