Allow filament change on any extruder during a print

During a multi-color print, we needed to replace filament on an extruder that was not currently active. At the moment, filament can only be changed on the extruder that is in use, making this impossible. As a workaround, we had to wait until that specific color was scheduled to print again. By then, the filament was not properly primed, which caused the print to fail. Allowing users to select and change filament on any extruder during an active print, regardless of whether it is currently in use, would help prevent failed prints, reduce downtime, and improve reliability for multi-material workflows. Proposed feature: Add the ability to manually select a specific extruder during a print and perform a filament change on it, even if it is not the active extruder. Benefits: Eliminates unnecessary waiting during long multi-color prints Improves usability and robustness of multi-extruder printing