typing: add type hints to `mercurial/utils/resourceutil.py`

The `except` path requires byte args (because of the byte based manipulation in
`_package_path()`), while the `else` case tolerates `AnyStr`.  Pytype was unable
to figure this out, and we should make sure the interface is the same for all
environments.

mercurial/utils/resourceutil.py

@@ -11,10 +11,18 b''
 import _imp
 import os
 import sys
+import typing
 
 from .. import pycompat
 
 
+if typing.TYPE_CHECKING:
+    from typing import (
+        BinaryIO,
+        Iterator,
+    )
+
+
 def mainfrozen():
     """return True if we are a frozen executable.
 
@@ -39,7 +47,7 b' if mainfrozen() and getattr(sys, "frozen'
     # leading "mercurial." off of the package name, so that these
     # pseudo resources are found in their directory next to the
     # executable.
-    def _package_path(package):
+    def _package_path(package: bytes) -> bytes:
         dirs = package.split(b".")
         assert dirs[0] == b"mercurial"
         return os.path.join(_rootpath, *dirs[1:])
@@ -49,7 +57,7 b' else:'
     datapath = os.path.dirname(os.path.dirname(pycompat.fsencode(__file__)))
     _rootpath = os.path.dirname(datapath)
 
-    def _package_path(package):
+    def _package_path(package: bytes) -> bytes:
         return os.path.join(_rootpath, *package.split(b"."))
 
 
@@ -72,11 +80,11 b' except (ImportError, AttributeError):'
     # importlib.resources was not found (almost definitely because we're on a
     # Python version before 3.7)
 
-    def open_resource(package, name):
+    def open_resource(package: bytes, name: bytes) -> "BinaryIO":
         path = os.path.join(_package_path(package), name)
         return open(path, "rb")
 
-    def is_resource(package, name):
+    def is_resource(package: bytes, name: bytes) -> bool:
         path = os.path.join(_package_path(package), name)
 
         try:
@@ -84,7 +92,7 b' except (ImportError, AttributeError):'
         except (IOError, OSError):
             return False
 
-    def contents(package):
+    def contents(package: bytes) -> "Iterator[bytes]":
         path = pycompat.fsdecode(_package_path(package))
 
         for p in os.listdir(path):
@@ -94,7 +102,7 b' except (ImportError, AttributeError):'
 else:
     from .. import encoding
 
-    def open_resource(package, name):
+    def open_resource(package: bytes, name: bytes) -> "BinaryIO":
         if hasattr(resources, 'files'):
             return (
                 resources.files(  # pytype: disable=module-attr
@@ -108,12 +116,12 b' else:'
                 pycompat.sysstr(package), pycompat.sysstr(name)
             )
 
-    def is_resource(package, name):
+    def is_resource(package: bytes, name: bytes) -> bool:
         return resources.is_resource(  # pytype: disable=module-attr
             pycompat.sysstr(package), encoding.strfromlocal(name)
         )
 
-    def contents(package):
+    def contents(package: bytes) -> "Iterator[bytes]":
         # pytype: disable=module-attr
         for r in resources.contents(pycompat.sysstr(package)):
             # pytype: enable=module-attr