iCal file generation might need review after Core PR

[jensschuppe]

See civicrm/civicrm-core#25723.

Custom Event Communication does this for making sure that HTML entities are being decoded in the ics file:

de.systopia.eventmessages/Civi/EventMessages/AttachmentProvider/ICal.php

Lines 73 to 78 in e703c1f

	$event_data = \CRM_Event_BAO_Event::getCompleteInfo('19800101', null, $event_id, null, false);
	foreach (['title', 'description', 'event_type', 'location', 'contact_email'] as $field) {
	if (isset($event_data[0][$field])) {
	$event_data[0][$field] = html_entity_decode($event_data[0][$field], ENT_QUOTES | ENT_HTML401, 'UTF-8');
	}
	}

The Core PR is to do this for the description field, so we might need to adapt our code when it gets merged.