Add customField in Fulfillment

[jonyw4]

Is your feature request related to a problem? Please describe.
I have some Vendure plugins to create labels to ship a fulfillment and I need to save that information in Fulfillment.

Describe the solution you'd like
Add customField in Fulfillment just like Orders.

[michaelbromley]

I'm going to add custom field support now, and display custom field data in the fulfillment card in the OrderDetail view of the Admin UI, but I will not make any UI/API changes for inputting custom field data until I've spent more time thinking about #529.

So for now you'll be able to programmatically set and query the custom field values in your own plugin code.

[jonyw4]

@michaelbromley Ok, For me for now will resolve. All fields that I need to put in Fulfillment will be used internally by the system. Thanks!