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/InodeWatcher.cpp

@@ -12,9 +12,9 @@
 
 namespace Kernel {
 
-ErrorOr<NonnullRefPtr<InodeWatcher>> InodeWatcher::try_create()
+ErrorOr<NonnullLockRefPtr<InodeWatcher>> InodeWatcher::try_create()
 {
-    return adopt_nonnull_ref_or_enomem(new (nothrow) InodeWatcher);
+    return adopt_nonnull_lock_ref_or_enomem(new (nothrow) InodeWatcher);
 }
 
 InodeWatcher::~InodeWatcher()