Breaking: #78899 - Remove extJSCODE from FormEngine result array

See Issue #78899

Description

The key extJSCODE in the array returned by FormEngine's Container and Element (initialized in AbstractNode->initializeResultArray()) has been removed.

Impact

JavaScript code added to extJSCODE by custom elements will not be evaluated anymore.

Affected Installations

Search extensions for the string extJSCODE. This array is used rather seldom, but if there are matches in combination with Backend Form classes, they should be adapted.

Migration

For a simple solution, add according JavaScript to the return key additionalJavaScriptPost for now. Both keys were used nearly identically anyway. Be aware that both keys additionalJavaScriptPost and additionalJavaScriptSubmit are target of a later removal as soon as a better JavaScript side event handling for those scenarios is in place. See if the current code injected at this point could be done with casual RequireJsModules instead already.