text: Title: Deprecate `Return` node in parsing model
  Body: In RF 5.0 we introduced the new `RETURN` statement (#4078) that made the old `[Return]` setting obsolete. Although there isn't yet any visible deprecation warning, the `[Return]` setting is considered deprecated and it will be eventually removed.
  
  In the parsing model we currently have a `Return` node refers to the `[Return]` setting while `RETURN` is represented by `ReturnStatement`. It would be better to rename the latter to just `Return` to be consistent with the `Break` and `Continue` nodes as well as with the execution side `Return` object. That would then require renaming the current `Return` to `ReturnSetting` until we can eventually remove it.
  
  Renaming nodes as discussed above is a backwards incompatible change and needs to wait for RF 7.0. To help with the transition, we can already now in RF 6.1 do some enhancements:
  
  - Add `ReturnSetting` as an alias for `Return` that tools like RoboTidy can use.
  - Enhance `ModelVisitor` so that the `Return` node will match also `visit_ReturnStatement` visitor methods.
  - Document that `Return` is deprecated and that `ReturnSetting` should be used instead.
  
  First two items are simple code changes. The last one is covered by mentioning this issue in the release notes.