zipimport: various fixes (#3701)

- allow path of find_module to be None (the default value)
- add undocumented find_loader and get_resource_reader
- greater consistency for __init__ param names

stdlib/2and3/zipimport.pyi

@@ -1,18 +1,29 @@
 """Stub file for the 'zipimport' module."""
 
-from typing import Optional
+import os
+import sys
+from typing import Any, List, Optional, Tuple, Union
 from types import CodeType, ModuleType
+if sys.version_info >= (3, 7):
+    from importlib.abc import ResourceReader
 
 class ZipImportError(ImportError): ...
 
 class zipimporter(object):
     archive: str
     prefix: str
-    def __init__(self, archivepath: str) -> None: ...
-    def find_module(self, fullname: str, path: str = ...) -> Optional[zipimporter]: ...
+    if sys.version_info >= (3, 6):
+        def __init__(self, path: Union[str, bytes, os.PathLike[Any]]) -> None: ...
+    else:
+        def __init__(self, path: Union[str, bytes]) -> None: ...
+    if sys.version_info >= (3,):
+        def find_loader(self, fullname: str, path: Optional[str] = ...) -> Tuple[Optional[zipimporter], List[str]]: ...  # undocumented
+    def find_module(self, fullname: str, path: Optional[str] = ...) -> Optional[zipimporter]: ...
     def get_code(self, fullname: str) -> CodeType: ...
     def get_data(self, pathname: str) -> str: ...
     def get_filename(self, fullname: str) -> str: ...
+    if sys.version_info >= (3, 7):
+        def get_resource_reader(self, fullname: str) -> Optional[ResourceReader]: ...  # undocumented
     def get_source(self, fullname: str) -> Optional[str]: ...
     def is_package(self, fullname: str) -> bool: ...
     def load_module(self, fullname: str) -> ModuleType: ...