Registration config for libraries are not respected in user projects

[chippmann]

Follow up issue of #658

If a library uses fqdn registration and defines a custom resource like:

package godot.tests.library.fqname

@RegisterClass
class CustomResource: Resource()

it's FQDN registration is: godot_tests_library_fqname_CustomResource.

But when used in a project which does not use FQDN registration and exported as a property:

@Export
@RegisterProperty
var wrongTypeHint = CustomResource()

it's type hint becomes CustomResource rather than godot_tests_library_fqname_CustomResource

This is true both ways.