Fix for Nova Deferred Field Support

[tzsk]

BUG FIX

Nova has the support for Deferred Fields. Meaning, the fields which get handled after the model is saved i.e. created or updated.

For those types of fields, the fill() method on the Field returns a closure. And that closure gets invoked after the Resource Model is saved. Refer to: Laravel\Nova\Http\Controllers\ResourceStoreController:41 & Laravel\Nova\Http\Controllers\ResourceUpdateController:38

Now, the bug is. If you put those types of fields in the Dependency Container it never gets handled.

So, for this package to support all scenarios, just filling the fields is not enough. We have to handle the deferred fields under the field list of Dependency Container (if any).

This PR is an attempt to fix that.

[jkudish]

Hi @wize-wiz, I work with @tzsk and I'm wondering if there's any chance you could take a look at this PR and get it merged? We'll have to fork the project otherwise, which I'd love to avoid doing!