[pywin32] Improve pythonwin.dde

Based on: https://github.com/mhammond/pywin32/blob/b312/pythonwin/ddemodule.cpp

Author: donbarbos

stubs/pywin32/pythonwin/dde.pyi

@@ -1,33 +1,36 @@
 # Can't generate with stubgen because:
 # "ImportError: This must be an MFC application - try 'import win32ui' first"
-APPCLASS_MONITOR: int
-APPCLASS_STANDARD: int
-APPCMD_CLIENTONLY: int
-APPCMD_FILTERINITS: int
-CBF_FAIL_ADVISES: int
-CBF_FAIL_ALLSVRXACTIONS: int
-CBF_FAIL_CONNECTIONS: int
-CBF_FAIL_EXECUTES: int
-CBF_FAIL_POKES: int
-CBF_FAIL_REQUESTS: int
-CBF_FAIL_SELFCONNECTIONS: int
-CBF_SKIP_ALLNOTIFICATIONS: int
-CBF_SKIP_CONNECT_CONFIRMS: int
-CBF_SKIP_DISCONNECTS: int
-CBF_SKIP_REGISTRATIONS: int
+from typing import Final
 
-def CreateConversation(Server, /): ...
-def CreateServer(): ...
-def CreateServerSystemTopic(): ...
-def CreateStringItem(name, /): ...
-def CreateTopic(name, /): ...
-
-MF_CALLBACKS: int
-MF_CONV: int
-MF_ERRORS: int
-MF_HSZ_INFO: int
-MF_LINKS: int
-MF_POSTMSGS: int
-MF_SENDMSGS: int
+import _win32typing
 
 class error(Exception): ...
+
+def CreateConversation(Server, /) -> _win32typing.PyDDEConv: ...
+def CreateServer() -> _win32typing.PyDDEServer: ...
+def CreateServerSystemTopic(): ...
+def CreateTopic(name: str, /) -> _win32typing.PyDDETopic: ...
+def CreateStringItem(name: str, /) -> _win32typing.PyDDEStringItem: ...
+
+APPCLASS_MONITOR: Final[int]
+APPCLASS_STANDARD: Final[int]
+APPCMD_CLIENTONLY: Final[int]
+APPCMD_FILTERINITS: Final[int]
+CBF_FAIL_ALLSVRXACTIONS: Final[int]
+CBF_FAIL_ADVISES: Final[int]
+CBF_FAIL_CONNECTIONS: Final[int]
+CBF_FAIL_EXECUTES: Final[int]
+CBF_FAIL_POKES: Final[int]
+CBF_FAIL_REQUESTS: Final[int]
+CBF_FAIL_SELFCONNECTIONS: Final[int]
+CBF_SKIP_ALLNOTIFICATIONS: Final[int]
+CBF_SKIP_CONNECT_CONFIRMS: Final[int]
+CBF_SKIP_DISCONNECTS: Final[int]
+CBF_SKIP_REGISTRATIONS: Final[int]
+MF_CALLBACKS: Final[int]
+MF_CONV: Final[int]
+MF_ERRORS: Final[int]
+MF_HSZ_INFO: Final[int]
+MF_LINKS: Final[int]
+MF_POSTMSGS: Final[int]
+MF_SENDMSGS: Final[int]