Visual Studio cannot build the Flutter engine currently as depot_tools removed ninja.exe: https://groups.google.com/a/chromium.org/g/chromium-dev/c/027jM6DLkIk

Solution:

1. Fix bug in depot_tools's ninja.py: depot_tool#4215121
2. Switch the engine to use the latest ninja.py from the depot_tools.