Detection of shim boot loader should be case insensitive

[tenzap]

Since e8ce9fe there is detection of the shim boot loader to have a better display of loader options.
This works fine when it is lowercase
But when the shim loader is uppercase SHIMX64.EFI, it doesn't detect that it's shim and therefore doesn't adjust the display accordingly.

Version 18 (checked on debian, version 18-2)

Even if I create the loader value in lower case (\EFI\debian\shimx64.efi), the firmware of the motherboard changes it to upper case.