Feature: #68600 - Introduced ResourceStorage SanitizeFileName signal

See forge#68600


In order to check whether an uploaded/newly added file already exists before uploading it or to ask for user preferences about already existing files only when needed, the final name for the uploaded file is needed.

In order to let extensions do custom sanitizing of a file name the signal sanitizeFileName is introduced in TYPO3\CMS\Core\Resource\ResourceStorage. The signal is emitted when ResourceStorage::sanitizeFileName or ResourceStorage::addFile are called.


All installations with extensions that use the PreFileAdd signal to change/sanitize a file name. This logic should be moved to the new sanitizeFileName signal.