gh-89554: Document _thread.LockType as a class

_thread.LockType is a class (the type of lock objects), but was documented
with the ".. data::" directive, so ":class:" cross-references to it cannot
resolve against a py:class target.

Switch the entry to ".. class::" and move it next to the lock methods it
describes, keeping the existing method anchors unchanged.

Author: gaborbernat

Doc/library/_thread.rst

@@ -36,11 +36,6 @@ This module defines the following constants and functions:
       This is now a synonym of the built-in :exc:`RuntimeError`.
 
 
-.. data:: LockType
-
-   This is the type of lock objects.
-
-
 .. function:: start_new_thread(function, args[, kwargs])
 
    Start a new thread and return its identifier.  The thread executes the
@@ -162,6 +157,11 @@ This module defines the following constants and functions:
    .. versionadded:: 3.2
 
 
+.. class:: LockType
+
+   This is the type of lock objects.
+
+
 Lock objects have the following methods: