Debounce validation

[icebob]

New formOption validateDebounceTime to debouncing the validate method:

{
    model: {
        name: "",
    },

    schema: {
        fields: [
            {
                type: "input",
                inputType: "text",
                label: "Name",
                model: "name",
                    validator: function(value, field, model){
                    return new Promise(resolve => {
                        setTimeout(() => {
                            if (value === "valid")
                                return resolve([]);

                            resolve([`invalid name: "${value}"`]);
                        }, 500);
                    });
                }
            }
        ]
    },

    formOptions: {
            validateAfterChanged: true,
            validateDebounceTime: 500
    }
}