Expose AddOrUpdateChild as a recipe using XPath + child XML

[DidierLoiseau]

What's changed?

Simple XML recipe that can add or update a child below the element(s) selected by XPath.

What's your motivation?

Provide more flexible ways of updating XML/pom files. In our specific case we need to configure openapi-generator-maven-plugin with <useJakartaEe>true</useJakartaEe> when it matches <generatorName>spring</generatorName>, following JavaxMigrationToJakarta (once this PR is merged, maybe it could be included there).

Anything in particular you'd like reviewers to focus on?

I had considered offering the option to add the child even when it already exists, but that wouldn’t be idempotent. I implemented an option to not replace the child in such a case, disabled by default.

I based this branch on top of #4532 so the former should be merged first and it’s not needed to review the changes on XPath implementation. I just wanted to use the XPath fixes in the tests of this new recipe.

Have you considered any alternatives or workarounds?

I don’t think any other equivalent recipe exists. ChangePluginConfiguration only allows to override the whole configuration.

Checklist

• I've added unit tests to cover both positive and negative cases
• I've read and applied the recipe conventions and best practices
• I've used the IntelliJ IDEA auto-formatter on affected files

[sambsnyd]

Thanks @DidierLoiseau !

[DidierLoiseau]

Thanks for merging @sambsnyd

I based this branch on top of #4532 so the former should be merged first

Sorry it seems I wrote former instead of latter there, so when you merged #4532 afterwards it created an empty commit, and c307b31 includes the changes of both 😕