Kernel: Move a bunch of generic devices code into new subdirectory

Author: https://github.com/supercomputer7
Commit: 4617c05a08
Pull-request: https://github.com/SerenityOS/serenity/pull/17909
Reviewed-by: https://github.com/Panky-codes ✅
Reviewed-by: https://github.com/gmta ✅

Kernel/Process.cpp

@@ -21,7 +21,7 @@
 #include <Kernel/API/POSIX/errno.h>
 #include <Kernel/API/POSIX/sys/limits.h>
 #include <Kernel/Arch/PageDirectory.h>
-#include <Kernel/Devices/NullDevice.h>
+#include <Kernel/Devices/Generic/NullDevice.h>
 #include <Kernel/FileSystem/Custody.h>
 #include <Kernel/FileSystem/OpenFileDescription.h>
 #include <Kernel/FileSystem/VirtualFileSystem.h>