Move wixtools to toolchain block

windows/Dockerfile

@@ -8,7 +8,10 @@ RUN [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tl
     choco install -y visualstudio2017-workload-vctools; \
     Start-Process "\"C:/Program Files (x86)/Microsoft Visual Studio/Installer/vs_installer.exe\"" -ArgumentList 'modify --installPath \"C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools\" --quiet --norestart --remove Microsoft.VisualStudio.Component.VC.CMake.Project' -NoNewWindow -Wait; \
     choco install -y cmake --version 3.12.2 --installargs "ADD_CMAKE_TO_PATH=System"; \
-    choco install -y git 7zip; \
+    choco install -y \
+        git \
+        7zip \
+        wixtoolset; \
     (New-Object Net.WebClient).DownloadFile('https://github.com/Kitware/ninja/releases/download/v1.8.2.g972a7.kitware.dyndep-1/ninja-1.8.2.g972a7.kitware.dyndep-1_i686-pc-windows-msvc.zip', 'C:/ninja.zip'); \
     7z e C:/ninja.zip -oC:/ninja -y; \
     Remove-Item C:/ninja.zip -Force; \
@@ -60,6 +63,3 @@ RUN python -m pip --no-cache-dir install --no-warn-script-location \
         scipy \
         matplotlib \
         pandas
-
-RUN choco install -y \
-    wixtoolset