bpo-44893: Implement EntryPoint as simple class with attributes. (GH-30150)

* bpo-44893: Implement EntryPoint as simple class and deprecate tuple access in favor of attribute access. Syncs with importlib_metadata 4.8.1.

* Apply refactorings found in importlib_metadata 4.8.2.

Lib/importlib/metadata/_functools.py

@@ -83,3 +83,22 @@ def method_cache(method, cache_wrapper=None):
     wrapper.cache_clear = lambda: None
 
     return wrapper
+
+
+# From jaraco.functools 3.3
+def pass_none(func):
+    """
+    Wrap func so it's not called if its first param is None
+
+    >>> print_text = pass_none(print)
+    >>> print_text('text')
+    text
+    >>> print_text(None)
+    """
+
+    @functools.wraps(func)
+    def wrapper(param, *args, **kwargs):
+        if param is not None:
+            return func(param, *args, **kwargs)
+
+    return wrapper