Breaking: #105686 - Avoid obsolete $charset in sanitizeFileName()
See forge#105686
Description
Class 
        \TYPO3\:
public function sanitizeFileName(string $fileName, string $charset = ''): stringhas been simplified to:
public function sanitizeFileName(string $fileName): stringClasses implementing the interface no longer need to take care of a second argument.
Impact
This most likely has little to no impact since the main API caller,
the core class 
        Resource never hands over the second
argument. Default implementing class 
        \TYPO3\
thus always fell back as if handling utf-8 strings.
Affected installations
Projects with instances implementing own FAL drivers using 
        Driver
may be affected.
Migration
Implementing classes should drop support for the second argument. It does
not collide with the interface if the second argument is kept, but core
code will never call method 
        sanitize with handing over
a value for a second argument.