FBBT: resolve bug registering native type handlers

[jsiirola]

Fixes # .

Summary/Motivation:

As part of #3558 we hit a bug where NumPy types were not getting correctly registered with the FBBT before child dispatcher. This resolves the error and adds a test covering it.

Changes proposed in this PR:

• Support automatic registration of native types for the FBBT before child dispatcher

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[mrmundt]

It is insane how small and impactful this change is.