Always set currentRecord when initializing widgets

[leofeyer]

First of all, this is not to be mistaken with $objCurrentRecord in the DCA, which we have recently reworked for Contao 5.

Our widgets have a currentRecord property, which is set when they are initialized:

contao/core-bundle/src/Resources/contao/classes/DataContainer.php

Lines 433 to 435 in e581d92

	$objWidget = new $strClass($strClass::getAttributesFromDca($arrData, $this->strInputName, $this->varValue, $this->strField, $this->strTable, $this));
	$objWidget->xlabel = $xlabel;
	$objWidget->currentRecord = $this->intId;

However, we are not doing this everywhere, so sometimes the value is unexpectedly null. This PR fixes that.