Comments from `YamlEditor.update`

[kekavc24]

For YamlEditor.remove, the objective was clear (even from the existing code). If a node is removed, remove comments that match that node.

However, for YamlEditor.update, it seems the update wants to keep the comment (evident from code. See except from list_mutations.dart).

tools/pkgs/yaml_edit/lib/src/list_mutations.dart

Lines 46 to 58 in da8a25c

	var end = getContentSensitiveEnd(currValue);
	if (end <= offset) {
	offset++;
	end = offset;
	valueString = ' $valueString';
	}
	return SourceEdit(offset, end - offset, valueString);
	} else {
	valueString = yamlEncodeFlow(newValue);
	return SourceEdit(offset, currValue.span.length, valueString);
	}
	}

---

My point is, these comments only pose a threat to block scalars. They could be captured and re-applied to the block scalar is a non-intrusive way.

Consider:

const yaml = ... // Some string from the examples below.

final editor = YamlEditor(
  yaml,
)..update([1], wrapAsYamlNode('taste', scalarStyle: ScalarStyle.FOLDED));

Block lists

# Before 
- eye
- knead # with this comment
- dough

# After
- eye
# with this comment
- >- 
  taste
- dough

--- # Or even this for readability
- eye

# with this comment
- >- 
  taste
- dough

Block maps

# Before
bit-flip: "0-to"
1: jumps # with this comment

# After
bit-flip: "0-to"
1:
  # with this comment
  >- 
  taste

---

We could do:

1. What I propose. This is similar to some examples in Comment causes issue with ScalarStyle.FOLDED #1935 but more contextual to value being inserted.
2. Truncate and remove the comment(s) for updates that add:
   1. Any node (block and flow)
   2. Block scalars only.
   3. Block nodes only

Both implementations are simple, improve package:yaml_edit, use the changes in #2240 and won't be a breaking change for most of the existing tests.

---

cc @jonasfj @sigurdm

Also see a draft of option 2.i where comments are removed from all nodes in block lists when _updateInList is called. #2315