Add IME support

[zekexiao]

CJK users general has a input method to input CJK char.
dlangui not handled WM_INPUT WM_IME message, so IME not in a right position (should display under the editing line).

dlangui:

windows notepad:

AvaloniaUI code here:
https://github.com/AvaloniaUI/Avalonia/blob/567a38ec7206df80cf81343fcabaa22f8db0e45c/src/Windows/Avalonia.Win32/WindowImpl.AppWndProc.cs#L676

Windows docs:
https://learn.microsoft.com/en-us/windows/win32/intl/input-method-manager

[GrimMaple]

#324 This issue is relevant. Same but for Linux basically :)

[GrimMaple]

Also, I added this (and other input method thing) to my list TODO list so I'll look into it when I get free time