Breaking: #106427 - File Abstraction Layer related changes 

Description 

In TYPO3 v14, the PHP code API for the File Abstraction Layer (FAL) has undergone some major changes, which might affect extension authors:

1. Most PHP code from FAL is now strongly typed by PHP native typing system
2. Some methods have been moved from AbstractFile to its concrete implementation within File as other derivatives should implement this on their own. The moved methods are: - AbstractFile->rename() - AbstractFile->copyTo() - AbstractFile->moveTo()
3. The FileInterface's method rename() has been removed as it is only necessary within the implementation of File.

4. Classes implementing FolderInterface must now implement FolderInterface::getSubFolder(), FolderInterface::getReadablePath() as well as FolderInterface::getFiles() and FolderInterface::searchFiles() to be interchangeable with the new Folder class.

   In previous implementations this was not possible to make Folder more interchangeable but this is a first step towards that process.

Impact 

Calling the PHP classes and methods from File Abstraction Layer directly might result in fatal PHP errors due to specific types required as method arguments.

Affected installations 

TYPO3 installations with third-party extensions that have used FAL API in a non-documented way.

Migration 

Ensure to hand in or expect proper PHP types when using or extending FAL API.

In addition, ensure to implement the new methods in your own Folder implementations or derivatives of AbstractFile.