TYPO3 Core

With https://github.com/TYPO3/TYPO3.CMS/commit/f274f58d0a10c5540a97fcd5a90f24559ee0b647#diff-d189334d4c1207ff3c0fd58820e4e596R125
the onChange behavior was moved into JavaScript land.
If you use an onChange instruction within flexform e.g https://github.com/TYPO3/TYPO3.CMS/blob/master/typo3/sysext/form/Configuration/FlexForms/FormFramework.xml#L13 this does not work anymore.

@see https://github.com/TYPO3/TYPO3.CMS/commit/f274f58d0a10c5540a97fcd5a90f24559ee0b647#diff-d189334d4c1207ff3c0fd58820e4e596R128

`$parameterArray['itemFormElName']` contains something like `data[tt_content]<sup>1</sup>[pi_flexform]` which is used by javascript to fetch the element by the name attribute https://github.com/TYPO3/TYPO3.CMS/commit/f274f58d0a10c5540a97fcd5a90f24559ee0b647#diff-aae54a23dc527b7e222319447f2fba5cR836

But the form element data attribute within the FlexForm context is resolved like `data[tt_content]<sup>1</sup>[pi_flexform][data][sDEF][lDEF][settings.persistenceIdentifier][vDEF]` so `FormEngine.requestConfirmationOnFieldChange` can not fetch the element and therefore can not show the onChange modal.

And since checkboxes are rendered without name attributes `FormEngine.getFieldElement` does not work (https://github.com/TYPO3/TYPO3.CMS/commit/f274f58d0a10c5540a97fcd5a90f24559ee0b647#diff-aae54a23dc527b7e222319447f2fba5cR836)

We can replace

`GeneralUtility::quoteJSvalue($parameterArray['itemFormElName'])`

with

`GeneralUtility::quoteJSvalue('data' . $options['elementBaseName'])`

here https://github.com/TYPO3/TYPO3.CMS/commit/f274f58d0a10c5540a97fcd5a90f24559ee0b647#diff-d189334d4c1207ff3c0fd58820e4e596R128
but this does not solve the issue with html elements without name attributes