dropping the node style creates a compatibility issue where quotes around "on" are dropped
because yaml.v3 interprets it as a string.
other yaml parsers interpret on as a bool value, and parse it as a bool rather than string.
fix: retain the original style so it is kept as quoted.
- fmt: don't drop the styles
- merge2: keep the style when merging elements
- setting a field: if changing the value of a scalar field, retain its style by default
