set(form_id, input_name, input_value) {
        this._checkInit(form_id);
        const input = this._collection[form_id].getInput(input_name);
        input.value = input_value;
    }
Set new value of real DOM input or virtual input
Actually fires change event and values are set in _attachChangeAndDefaultFileEvent()

@param {string} form_id
@param {string} input_name
@param {string|Blob|Object} input_value