Review YamlEditor line ending to be more aligned with how the SDK does it

[FMorschel]

Based on dart-lang/sdk#60234 I think we can give some attention to the YamlEditor here, considering line endings.

We could probably copy the work at:

https://github.com/dart-lang/sdk/blob/1499a30cd560b93ea692b5dfa78dbd01275dd720/pkg/analysis_server_plugin/lib/edit/correction_utils.dart#L53-L73

FYI @DanTup