add wrap-return-self to change default behavior from returning a copy to a reference

[timosachsenberg]

https://github.com/OpenMS/OpenMS/pull/7249#discussion_r1419076141

[jpfeuffer]

It should not really be changing the default behaviour. It should only be used for methods that return some changed version of "this/self". For other things, returning references should barely ever be used since we have no mechanism for usage counts.