Add a couple missing tkinter things (#13149)

stdlib/@tests/stubtest_allowlists/common.txt

@@ -95,7 +95,6 @@ multiprocessing.pool.Pool.Process
 multiprocessing.pool.ThreadPool.Process
 multiprocessing.synchronize.Semaphore.get_value
 tkinter.Misc.config
-tkinter.font.Font.counter
 
 
 # ==========

stdlib/tkinter/__init__.pyi

@@ -627,7 +627,8 @@ class Misc:
     def __getitem__(self, key: str) -> Any: ...
     def cget(self, key: str) -> Any: ...
     def configure(self, cnf: Any = None) -> Any: ...
-    # TODO: config is an alias of configure, but adding that here creates lots of mypy errors
+    # TODO: config is an alias of configure, but adding that here creates
+    # conflict with the type of config in the subclasses. See #13149
 
 class CallWrapper:
     func: Incomplete

stdlib/tkinter/font.pyi

@@ -1,7 +1,8 @@
 import _tkinter
+import itertools
 import sys
 import tkinter
-from typing import Any, Final, Literal, TypedDict, overload
+from typing import Any, ClassVar, Final, Literal, TypedDict, overload
 from typing_extensions import TypeAlias
 
 if sys.version_info >= (3, 9):
@@ -40,6 +41,7 @@ class _MetricsDict(TypedDict):
 class Font:
     name: str
     delete_font: bool
+    counter: ClassVar[itertools.count[int]]  # undocumented
     def __init__(
         self,
         # In tkinter, 'root' refers to tkinter.Tk by convention, but the code