Allow DeserializationProblemHandler to respond to primitive types

[nhtzr]

When registering a DeserializationProblemHandler, one is allowed to override its methods to return a converted value.

DeserializationContext has a sanity check in case the problem handler returns an Object that is not assignable to the property that is currently being parsed.

However for properties that rely on primitive types, this sanity check will always fail due to autoboxing.

(As a side note: Some upper code swallows the generated exception by this check, so the user only sees the original problem that caused the Problem Handler to be invoked in the first place even though the sanity check builds and throws a proper exception)

This PR add an extra comparison for primitive type (against their wrapped versions) while moving the sanity check into its own method.

Please let me know if I'm missing anything!
Thank you

[cowtowncoder]

Ok I idea seems reasonable, thank you for suggesting it. I can probably clean it up a little bit (there are helper methods for finding wrapper types), but basic idea seems sound.

Thank you for contributing this!

[cowtowncoder]

One request: do you happen to have a reproduction of the problem? Would be good to verify fix as well as have a regression test.

[nhtzr]

Sure, no problem.
I couldn't find a way to run it inside the repo, but I've made a little project that reproduces the issue:
https://github.com/nhtzr/jackson-databind/tree/test

[cowtowncoder]

Thank you again for reporting this, showing how to fix it.
I ended up merging changes manually since these are needed for 2.9 (although I did actually merge them in 2.8 just in case there'll be one last patch), but the idea is same.

Fix will be in 2.9.2.