gh-108751: Add copy.replace() function (GH-108752)

It creates a modified copy of an object by calling the object's
__replace__() method.

It is a generalization of dataclasses.replace(), named tuple's _replace()
method and replace() methods in various classes, and supports all these
stdlib classes.

Lib/inspect.py

@@ -2870,6 +2870,8 @@ class Parameter:
 
         return formatted
 
+    __replace__ = replace
+
     def __repr__(self):
         return '<{} "{}">'.format(self.__class__.__name__, self)
 
@@ -3130,6 +3132,8 @@ class Signature:
         return type(self)(parameters,
                           return_annotation=return_annotation)
 
+    __replace__ = replace
+
     def _hash_basis(self):
         params = tuple(param for param in self.parameters.values()
                              if param.kind != _KEYWORD_ONLY)