Arbitrary TypoScript execution on system extension form
The new system extension form can be used to render custom FORM elements as well as regular cObjects like TEXT or COA.
Since the form wizard can be used by any editor in the backend and writes data to the field bodytext, this can also be used to execute arbitrary TypoScript without further access checks.
This change introduces two defined and allowed content elements "header" and "textblock" that can be defined by using the form wizard. If the TypoScript that was generated by the mentioned wizard is rendered, regular cObjects are disabled. If the FORM or FORM_INT cObject is used directly from a TypoScript template, all possible cObjects can still be used.