[Analyzers][CPP]Turn on C26495 and fix code (#21163)

C26495: A member variable isn't initialized by a constructor or by an initializer.
Fixing occurrences with default member initialization.

src/modules/MeasureTool/MeasureToolCore/ScreenCapturing.cpp

@@ -35,7 +35,7 @@ class D3DCaptureState final
     winrt::IDirect3DDevice device;
     winrt::com_ptr<IDXGISwapChain1> swapChain;
 
-    winrt::SizeInt32 frameSize;
+    winrt::SizeInt32 frameSize{};
     HMONITOR monitor = {};
     winrt::DirectXPixelFormat pixelFormat;