bpo-42251: Add gettrace and getprofile to threading (GH-23125)

This allows to retrieve the functions that were set in these two, which might differ from sys.gettrace and sys.getprofile within a thread.
diff --git a/Doc/library/threading.rst b/Doc/library/threading.rst
index 7eb12fe..e05486f 100644
--- a/Doc/library/threading.rst
+++ b/Doc/library/threading.rst
@@ -121,6 +121,17 @@
    :meth:`~Thread.run` method is called.
 
 
+.. function:: gettrace()
+
+   .. index::
+      single: trace function
+      single: debugger
+
+   Get the trace function as set by :func:`settrace`.
+
+   .. versionadded:: 3.10
+
+
 .. function:: setprofile(func)
 
    .. index:: single: profile function
@@ -130,6 +141,15 @@
    :meth:`~Thread.run` method is called.
 
 
+.. function:: getprofile()
+
+   .. index:: single: profile function
+
+   Get the profiler function as set by :func:`setprofile`.
+
+   .. versionadded:: 3.10
+
+
 .. function:: stack_size([size])
 
    Return the thread stack size used when creating new threads.  The optional