Merge some simple classes' type stubs back to source (#2576)

Co-authored-by: Enrico Minack <github@enrico.minack.dev>

github/InputFileContent.py

@@ -26,7 +26,12 @@
 #                                                                              #
 ################################################################################
 
-import github.GithubObject
+
+from __future__ import annotations
+
+from typing import Any
+
+from github.GithubObject import NotSet, Opt, is_defined, is_optional
 
 
 class InputFileContent:
@@ -34,24 +39,17 @@ class InputFileContent:
     This class represents InputFileContents
     """
 
-    def __init__(self, content, new_name=github.GithubObject.NotSet):
-        """
-        :param content: string
-        :param new_name: string
-        """
-
+    def __init__(self, content: str, new_name: Opt[str] = NotSet):
         assert isinstance(content, str), content
-        assert new_name is github.GithubObject.NotSet or isinstance(
-            new_name, str
-        ), new_name
-        self.__newName = new_name
-        self.__content = content
+        assert is_optional(new_name, str), new_name
+        self.__newName: Opt[str] = new_name
+        self.__content: str = content
 
     @property
-    def _identity(self):
-        identity = {
+    def _identity(self) -> dict[str, str]:
+        identity: dict[str, Any] = {
             "content": self.__content,
         }
-        if self.__newName is not github.GithubObject.NotSet:
+        if is_defined(self.__newName):
             identity["filename"] = self.__newName
         return identity