MergedYamlMapping wipes out comments

When I use `MergedYamlMapping` with `overrideConflicts`, the resulting YAML file loses all comments from the original YAML on merge. Without producing an entire example:
```java
final YamlMapping updatedYaml = new MergedYamlMapping(oldYaml, newYaml, true);
System.out.println("OLD------------");
System.out.println(oldYaml.toString());
System.out.println("NEW------------");
System.out.println(newYaml.toString());
System.out.println("UPDATED--------");
System.out.println(updatedYaml.toString());
System.out.println("---------------");
```

Produces:
```
[INFO] OLD------------
[INFO] apiVersion: v2
name: Helm Chart Template
description: A Helm chart for Kubernetes
# Library charts provide useful utilities or functions for the chart developer. They're included as
# a dependency of application charts to inject those utilities and functions into the rendering
# pipeline. Library charts do not define any templates and therefore cannot be deployed.
type: application
# This is the chart version. This version number should be incremented each time you make changes
# to the chart and its templates, including the app version.
# Versions are expected to follow Semantic Versioning (https://semver.org/)
version: 0.0.0
# This is the version number of the application being deployed. This version number should be
# incremented each time you make changes to the application. Versions are not expected to
# follow Semantic Versioning. They should reflect the version the application is using.
# It is recommended to use it with quotes.
appVersion: 0.0.0
[INFO] NEW------------
[INFO] name: Mock Java Back End Service
description: A mock Java (Quarkus) back end service project used as a sandbox for testing CI processes.
version: "0.0.2-SNAPSHOT"
appVersion: "0.0.2-SNAPSHOT"
[INFO] UPDATED--------
[INFO] apiVersion: v2
name: Mock Java Back End Service
description: A mock Java (Quarkus) back end service project used as a sandbox for testing CI processes.
# Library charts provide useful utilities or functions for the chart developer. They're included as
# a dependency of application charts to inject those utilities and functions into the rendering
# pipeline. Library charts do not define any templates and therefore cannot be deployed.
type: application
version: "0.0.2-SNAPSHOT"
appVersion: "0.0.2-SNAPSHOT"
[INFO] ---------------
```

Note how the original has comments while the updated does not. The second you enable `overrideConflicts`, all comments are lost in the resulting merge on any item that is overridden.