Filter for default post types enabled?

Hello,

First off, thank you for this very straightforward plugin.

I have a Multisite installation with plenty of sites and I'm looking for a way to add some custom post types to the list of enabled post types for all of my current and future sites.

Would you be interested to add a filter that allows other developers to add custom post types to the list of default post types enabled for duplication?

The point would be for developers to be able to do something like that:

function my_duplicate_post_default_post_types_enabled($post_types) {
	return array_merge($post_types, array('mycpt1', 'mycpt2', 'mycpt3'));
}
add_filter('duplicate_post_default_post_types_enabled', 'my_duplicate_post_default_post_types_enabled');

I will submit a pull request shortly to show what I mean.

Locate where the plugin defines the default post types enabled for duplication and inspect any existing filter registration. Confirm how post types are handled across WordPress multisite sites, then verify that the proposed filter can add custom types for current and future sites without changing existing defaults.