bpo-40428: Remove PyTuple_ClearFreeList() function (GH-19769)

Remove the following function from the C API:

* PyAsyncGen_ClearFreeLists()
* PyContext_ClearFreeList()
* PyDict_ClearFreeList()
* PyFloat_ClearFreeList()
* PyFrame_ClearFreeList()
* PyList_ClearFreeList()
* PySet_ClearFreeList()
* PyTuple_ClearFreeList()

Make these functions private, move them to the internal C API and
change their return type to void.

Call explicitly PyGC_Collect() to free all free lists.

Note: PySet_ClearFreeList() did nothing.
diff --git a/Objects/frameobject.c b/Objects/frameobject.c
index 533186b..6d288b5 100644
--- a/Objects/frameobject.c
+++ b/Objects/frameobject.c
@@ -1200,11 +1200,9 @@
 }
 
 /* Clear out the free list */
-int
-PyFrame_ClearFreeList(void)
+void
+_PyFrame_ClearFreeList(void)
 {
-    int freelist_size = numfree;
-
     while (free_list != NULL) {
         PyFrameObject *f = free_list;
         free_list = free_list->f_back;
@@ -1212,13 +1210,12 @@
         --numfree;
     }
     assert(numfree == 0);
-    return freelist_size;
 }
 
 void
 _PyFrame_Fini(void)
 {
-    (void)PyFrame_ClearFreeList();
+    _PyFrame_ClearFreeList();
 }
 
 /* Print summary info about the state of the optimized allocator */