interfaces: convert the dirstate zope interface to a Protocol class

This is a small trial run for converting the repository interfaces enmasse, in
the same series of steps.  I'm not sure that this current code is valid (it has
zope attribute fields, and it's missing all of the `self` args on its functions,
but that was the previous state of things, and made PyCharm really unhappy).
But it will be easier to review the repository interface changes if this change
is separate from adding `self` and dropping the zope attributes all over.

Having an empty constructor in a protocol is weird.  I'm not sure if these args
should be converted to fields that all subclasses would have, and comments
around existing attributes say some should be going away.  Comment it out for
now so that it's not in the way, but also not forgotten.

mercurial/interfaces/dirstate.py

@@ -2,26 +2,32 from __future__ import annotations
 
 import contextlib
 
+from typing import (
+    Protocol,
+)
+
 from . import util as interfaceutil
 
 
-class idirstate(interfaceutil.Interface):
-    def __init__(
-        opener,
-        ui,
-        root,
-        validate,
-        sparsematchfn,
-        nodeconstants,
-        use_dirstate_v2,
-        use_tracked_hint=False,
-    ):
-        """Create a new dirstate object.
-
-        opener is an open()-like callable that can be used to open the
-        dirstate file; root is the root of the directory tracked by
-        the dirstate.
-        """
+class idirstate(Protocol):
+    # TODO: convert these constructor args to fields?
+    # def __init__(
+    #     self,
+    #     opener,
+    #     ui,
+    #     root,
+    #     validate,
+    #     sparsematchfn,
+    #     nodeconstants,
+    #     use_dirstate_v2,
+    #     use_tracked_hint=False,
+    # ):
+    #     """Create a new dirstate object.
+    #
+    #     opener is an open()-like callable that can be used to open the
+    #     dirstate file; root is the root of the directory tracked by
+    #     the dirstate.
+    #     """
 
     # TODO: all these private methods and attributes should be made
     # public or removed from the interface.