Make initial value (third parameter of useForm) dynamic

[sot1986]

Like for the method and url, it would be helpful to have also initial value originated by function.

Example are:

• initial function is created looking at a computed property values (fetched asynchronously from backend)
• when you create any object and you use same component for creation or editing (component is not refreshed on success).
• if you watch any dinamic variable to trigger form reset (typeing search values should reset the query cursor for example).

Thank you.