wpf: force builtin glyphs (#18906)

They're much prettier, but some users may not be 100% happy.

Author: DHowett

src/cascadia/TerminalControl/HwndTerminal.cpp

@@ -972,6 +972,7 @@ void _stdcall TerminalSetTheme(void* terminal, TerminalTheme theme, LPCWSTR font
         publicTerminal->_terminal->SetCursorStyle(static_cast<Microsoft::Console::VirtualTerminal::DispatchTypes::CursorStyle>(theme.CursorStyle));
 
         publicTerminal->_desiredFont = { fontFamily, 0, DEFAULT_FONT_WEIGHT, static_cast<float>(fontSize), CP_UTF8 };
+        publicTerminal->_desiredFont.SetEnableBuiltinGlyphs(true);
         publicTerminal->_UpdateFont(newDpi);
     }