Kernel: Make self-contained locking smart pointers their own classes

Until now, our kernel has reimplemented a number of AK classes to
provide automatic internal locking:

- RefPtr
- NonnullRefPtr
- WeakPtr
- Weakable

This patch renames the Kernel classes so that they can coexist with
the original AK classes:

- RefPtr => LockRefPtr
- NonnullRefPtr => NonnullLockRefPtr
- WeakPtr => LockWeakPtr
- Weakable => LockWeakable

The goal here is to eventually get rid of the Lock* classes in favor of
using external locking.

Kernel/FileSystem/Custody.h

@@ -8,17 +8,17 @@
 
 #include <AK/Error.h>
 #include <AK/IntrusiveList.h>
-#include <AK/RefPtr.h>
 #include <Kernel/Forward.h>
 #include <Kernel/KString.h>
 #include <Kernel/Library/ListedRefCounted.h>
+#include <Kernel/Library/LockRefPtr.h>
 #include <Kernel/Locking/SpinlockProtected.h>
 
 namespace Kernel {
 
 class Custody : public ListedRefCounted<Custody, LockType::Spinlock> {
 public:
-    static ErrorOr<NonnullRefPtr<Custody>> try_create(Custody* parent, StringView name, Inode&, int mount_flags);
+    static ErrorOr<NonnullLockRefPtr<Custody>> try_create(Custody* parent, StringView name, Inode&, int mount_flags);
 
     ~Custody();
 
@@ -35,9 +35,9 @@ public:
 private:
     Custody(Custody* parent, NonnullOwnPtr<KString> name, Inode&, int mount_flags);
 
-    RefPtr<Custody> m_parent;
+    LockRefPtr<Custody> m_parent;
     NonnullOwnPtr<KString> m_name;
-    NonnullRefPtr<Inode> m_inode;
+    NonnullLockRefPtr<Inode> m_inode;
     int m_mount_flags { 0 };
 
     mutable IntrusiveListNode<Custody> m_all_custodies_list_node;