Kernel: Implement read-only FAT12/16/32 driver with long name support

You can now mount FAT filesystems! This code might not work perfectly
but my quick testing seemed to work on all (FAT12/16/32) variants.

kernel/CMakeLists.txt

@@ -32,6 +32,8 @@ set(KERNEL_SOURCES
 	kernel/FS/DevFS/FileSystem.cpp
 	kernel/FS/Ext2/FileSystem.cpp
 	kernel/FS/Ext2/Inode.cpp
+	kernel/FS/FAT/FileSystem.cpp
+	kernel/FS/FAT/Inode.cpp
 	kernel/FS/FileSystem.cpp
 	kernel/FS/Inode.cpp
 	kernel/FS/Pipe.cpp