Compatible with "fcitx5" envrionment variable (#16434)

src/Avalonia.FreeDesktop/DBusIme/X11DBusImeHelper.cs

@@ -12,6 +12,8 @@ namespace Avalonia.FreeDesktop.DBusIme
             {
                 ["fcitx"] = static conn =>
                     new DBusInputMethodFactory<FcitxX11TextInputMethod>(_ => new FcitxX11TextInputMethod(conn)),
+                ["fcitx5"] = static conn =>
+                    new DBusInputMethodFactory<FcitxX11TextInputMethod>(_ => new FcitxX11TextInputMethod(conn)),
                 ["ibus"] = static conn =>
                     new DBusInputMethodFactory<IBusX11TextInputMethod>(_ => new IBusX11TextInputMethod(conn))
             };