Make use of JSONAssert in public API optional

[philwebb]

See spring-projects/spring-boot#15967 (comment) for details.

The user is suggesting that we consider an alternative to org.skyscreamer:jsonassert since there's little maintenance activity and little appetite to fix the split package issue.

If we do consider something else, we might be able to have JsonTester adapt to either library.

[snicoll]

Good timing considering that stuff is partially moving to Spring Framework and this gives us an opportunity to adapt things a bit.

[snicoll]

We could soften that particular use in the linked issue but Spring Framework 6.2 has more use of JSONAssert with the introduction of the AssertJ support. So if we want to move to something else, we could consider JsonUnit but it already depends on Spring.

I don't see us relying on JsonUnit at this stage (@lukas-krecan). @philwebb did you have any other candidates in mind?

[philwebb]

It doesn't look like there's any single candidate that would work as a drop-in replacement, but we could perhaps isolate ourselves a little by not using JSONAssert types in our own API.

I sketched something at https://github.com/philwebb/spring-framework/tree/gh-32791