Better support for packages: rubocop -V

[marcandre]

It would be nice if there was a way for packages like rubocop-performance/rspec/... to "register" themselves so we could output their versions in rubocop -V.

For example I couldn't confirm in rubocop/rubocop-performance#200 that the report was due to an older version of rubocop-performance.

[koic]

-V option has been extended from RuboCop 1.0 for extension cop versions.
#8908

e.g.

% rubocop -V
1.4.2 (using Parser 2.7.2.0, rubocop-ast 1.2.0, running on ruby 3.0.0 x86_64-darwin19)
  - rubocop-performance 1.9.1
  - rubocop-rspec 2.0.0

I've updated the issue template example for users by #9126.