Load initial options by default

[AkselMeola]

It would be very useful if the initial options in responsive mode could be loaded without specifying a non-empty default value.

At the moment the initial Ajax call is only done if there's a value. But in case there is no sensible default and the initial options depend on some other field/parent then nothing is loaded.

I think there should be an option to load initial options either using parent field value or by providing the initial query parameters to the field.

As of now:

// FormField.vue

// If field is responsive, do we have any initial values
if (this.field.value) {
    return this.loadInitialOptions(this.field.value);
}