AtlasEngine: Improve RDP performance (#13816)

Direct2D is able to detect remote connections and will switch to sending
draw commands across RDP instead of rendering the data on the server.
This reduces the amount of data that needs to be transmitted as well
as the CPU load of the server, if it has no GPU installed.
This commit changes `AtlasEngine` to render with just Direct2D if a software or
remote device was chosen by `D3D11CreateDevice`. Selecting the DXGI adapter the
window is on explicitly in the future would allow us to be more precise here.

This new rendering mode doesn't implement some of the more fancy features just
yet, like inverted cursors or coloring a single wide glyph in multiple colors.
It reuses most existing facilities and uses the existing tile hash map to cache
DirectWrite text layouts to improve performance. Unfortunately this does incur
a fairly high memory overhead of approximately 25MB for a 120x30 viewport.

Additional drive-by changes include:
* Treat the given font size exactly as its given without rounding
  Apparently we don't really need to round the font size to whole pixels
* Stop updating the const buffer on every frame
* Support window resizing if `debugGeneralPerformance` is enabled

Closes #13079

## Validation Steps Performed
* Tested fairly exhaustively over RDP ✅

src/renderer/atlas/AtlasEngine.api.cpp

@@ -606,7 +606,8 @@ void AtlasEngine::_resolveFontMetrics(const wchar_t* requestedFaceName, const Fo
     // Point sizes are commonly treated at a 72 DPI scale
     // (including by OpenType), whereas DirectWrite uses 96 DPI.
     // Since we want the height in px we multiply by the display's DPI.
-    const auto fontSizeInPx = std::roundf(requestedSize.Y / 72.0f * _api.dpi);
+    const auto fontSizeInDIP = requestedSize.Y / 72.0f * 96.0f;
+    const auto fontSizeInPx = requestedSize.Y / 72.0f * _api.dpi;
 
     const auto designUnitsPerPx = fontSizeInPx / static_cast<float>(metrics.designUnitsPerEm);
     const auto ascent = static_cast<float>(metrics.ascent) * designUnitsPerPx;
@@ -687,7 +688,7 @@ void AtlasEngine::_resolveFontMetrics(const wchar_t* requestedFaceName, const Fo
 
         fontMetrics->fontCollection = std::move(fontCollection);
         fontMetrics->fontName = std::move(fontName);
-        fontMetrics->fontSizeInDIP = fontSizeInPx / static_cast<float>(_api.dpi) * 96.0f;
+        fontMetrics->fontSizeInDIP = fontSizeInDIP;
         fontMetrics->baselineInDIP = baseline / static_cast<float>(_api.dpi) * 96.0f;
         fontMetrics->advanceScale = cellWidth / advanceWidth;
         fontMetrics->cellSize = { cellWidth, cellHeight };