Breaking: #97451 - Removed BackendController page hooks

See forge#97451

Description

The hooks $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['typo3/backend.php']['constructorPostProcess'], $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['typo3/backend.php']['renderPreProcess'], and $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['typo3/backend.php']['renderPostProcess'] have been removed in favor of a new PSR-14 event \TYPO3\CMS\Backend\Controller\Event\AfterBackendPageRenderEvent.

Additionally, the BackendController->addCss() method has been removed without replacement, as it is no longer used.

Impact

Any hook implementation registered is not executed anymore in TYPO3 v12.0+. The extension scanner will report possible usages.

Affected Installations

All TYPO3 installations using this hook in custom extension code.

Migration

The hooks are removed without deprecation in order to allow extensions to work with TYPO3 v11 (using the hook) and v12+ (using the new event).

Use the PSR-14 event as an improved replacement.