bbatsov/rubocop

### New features

* [#9125](https://github.com/rubocop/rubocop/issues/9125): Allow ConfigObsoletion to be extended by other RuboCop libraries. ([@dvandersluis][])
* [#9182](https://github.com/rubocop/rubocop/pull/9182): Support auto-correction for `Style/RedundantArgument`. ([@koic][])
* [#9186](https://github.com/rubocop/rubocop/pull/9186): Support auto-correction for `Style/FloatDivision`. ([@koic][])
* [#9167](https://github.com/rubocop/rubocop/pull/9167): Support auto-correct for `StyleSingleLineBlockParams`. ([@koic][])

### Bug fixes

* [#9177](https://github.com/rubocop/rubocop/pull/9177): Remove back-ref related code from `Style/SpecialGlobalVars`. ([@r7kamura][])
* [#9160](https://github.com/rubocop/rubocop/issues/9160): Fix an incorrect auto-correct for `Style/IfUnlessModifier` and `Style/SoleNestedConditional` when auto-correction conflicts for guard condition. ([@koic][])
* [#9174](https://github.com/rubocop/rubocop/issues/9174): Handle send nodes with unparenthesized arguments in `Style/SoleNestedConditional`. ([@dvandersluis][])
* [#9184](https://github.com/rubocop/rubocop/issues/9184): `Layout/EmptyLinesAroundAttributeAccessor` fails if the attr_accessor is the last line of the file. ([@tas50][])

### Changes

* [#9171](https://github.com/rubocop/rubocop/pull/9171): Add "did you mean" message when failing due to invalid cops in configuration. ([@dvandersluis][])
* [#8897](https://github.com/rubocop/rubocop/issues/8897): Change `Style/StringConcatenation` to accept line-end concatenation between two strings so that `Style/LineEndConcatenation` can handle it instead. ([@dvandersluis][])
* [#9172](https://github.com/rubocop/rubocop/pull/9172): Add `Style/PerlBackrefs` targets and change message more detailed. ([@r7kamura][])
* [#9187](https://github.com/rubocop/rubocop/pull/9187): Update formatters to output `[Correctable]` for correctable offenses. ([@dvandersluis][])
* [#9169](https://github.com/rubocop/rubocop/pull/9169): Add obsoletion warnings for `Performance/*` and `Rails/*` which are in separate gems now. ([@dvandersluis][])

[@dvandersluis]: https://github.com/dvandersluis
[@koic]: https://github.com/koic
[@r7kamura]: https://github.com/r7kamura
[@tas50]: https://github.com/tas50