[WIP] try to support Jackson 3

[pjfanning]

• very early changes
• a long way to go

[cowtowncoder]

We can probably drop Hibernate 4 support? I'll see if I can see D/L info from Maven Central.

And hibernate5_2-test should be removed (or pom.xml there is).

EDIT: could not find D/L stats; old OSSRH did have those but can no longer log in and nothing else has downloads stats. By deps difference b/w H5/H4 not huge (altho slightly in H5 favor) but no idea how actual usage is:

• https://libraries.io/maven/com.fasterxml.jackson.datatype:jackson-datatype-hibernate4 -- 107/40 dep-by
• https://libraries.io/maven/com.fasterxml.jackson.datatype:jackson-datatype-hibernate5 -- 142/52 dep-by

[cowtowncoder]

Already good progress: just 3 failures (for Hibernate 7, I assume others would fare similarly)

[pjfanning]

Already good progress: just 3 failures (for Hibernate 7, I assume others would fare similarly)

The idea is to get the Hibernate 7 build working first and then to enable the others again.
I have already made most of the changes in the other modules too but they still need more work to fully fix.

[pjfanning]

With hibernate 6 and 7. there is now just one broken test - related to lazy loading and I'm not yet sure how to fix it.
This LazyLoadingTest.testSerializeIdentifierFeature test is broken everywhere.
There are a couple of other test failures for Hibernate 4 and both variants of Hibernate 5.