Kernel: Remove a bunch of duplicate forward declarations

Kernel/FileSystem/FileDescription.h

@@ -38,14 +38,6 @@
 
 namespace Kernel {
 
-class CharacterDevice;
-class File;
-class MasterPTY;
-class Process;
-class Region;
-class Socket;
-class TTY;
-
 class FileDescription : public RefCounted<FileDescription> {
     MAKE_SLAB_ALLOCATED(FileDescription)
 public:

Kernel/Forward.h

@@ -45,6 +45,7 @@ class KBuffer;
 class KResult;
 class LocalSocket;
 class MappedROM;
+class MasterPTY;
 class PageDirectory;
 class PerformanceEventBuffer;
 class PhysicalPage;