Fix the color of marks (#16106)

Guess what _doesn't_ have the same layout as a bitmap? A `til::color`.

Noticed in 1.19.

Regressed in #16006

(cherry picked from commit 1745857)
Service-Card-Id: 90758500
Service-Version: 1.19

src/cascadia/TerminalControl/TermControl.cpp

@@ -359,9 +359,10 @@ namespace winrt::Microsoft::Terminal::Control::implementation
                 const auto end = beg + pipHeight * stride;
                 for (; beg < end; beg += stride)
                 {
-                    // Coincidentally a til::color has the same RGBA format as the bitmap.
+                    // a til::color does NOT have the same RGBA format as the bitmap.
 #pragma warning(suppress : 26490) // Don't use reinterpret_cast (type.1).
-                    std::fill_n(reinterpret_cast<til::color*>(beg), pipWidth, color);
+                    const DWORD c = 0xff << 24 | color.r << 16 | color.g << 8 | color.b;
+                    std::fill_n(reinterpret_cast<DWORD*>(beg), pipWidth, c);
                 }
             };