Cerbero CI on Windows

Deployment would happen on the same Docker-on-Windows setup as gst-build. Rough task list that I anticipate currently:

• Ship MSYS/MinGW inside the Docker image
  • Download latest mingw-get: https://osdn.net/projects/mingw/releases/p15522 (current latest is mingw-get-0.6.3-mingw32-pre-20170905-1-bin.zip)
  • Extract inside C:\MinGW
  • Install the necessary packages: C:\MinGW\bin\mingw-get.exe install msys-base mingw32-base mingw-developer-toolkit
  • After installation C:\MinGW\bin\mingw-get.exe can be used to update the installation with mingw-get update and mingw-get upgrade (this should be in the list of commands that run for each job)
• Ship non-MSYS cerbero dependencies
  • Figure out how to do unattended installs of other Cerbero deps on Windows
    • Username must not have spaces
    • Git (already in the image)
    • Visual Studio Community 2017 or newer (already in the image)
    • CMake
      • Download MSI (latest x64, no particular install path or version reqs), then run
      • msiexec -i c:/path/to/cmake-3.16.1-win64-x64.msi -quiet -norestart -log c:/path/to/install.log ADD_CMAKE_TO_PATH=System
    • Python
      • Must not be installed into a path with spaces
    • WiX
      • wix311.exe /install /quiet /norestart (no special version reqs or install path reqs)
• Write CI scripts for running Cerbero on Windows (!334 (merged))
  • Figure out how to run Cerbero in the MSYS environment when using Docker
    • Cerbero on Windows has to be run from inside the MSYS shell, which sets up the MSYS env for building Autotools recipes
    • C:\MinGW\msys\1.0\bin\sh.exe --login -c 'C:/path/to/cerbero-uninstalled [args]' (needs cerbero!372 (merged))
• Investigate how to use ccache for Autotools recipes (it's supposed to build and run just fine under mingw)
  • There's also a ccache fork with support for MSVC: https://github.com/cristianadam/ccache/releases

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Latest work by @alatiera is in https://gitlab.freedesktop.org/alatiera/gst-ci/-/commits/alatiera/cerbero-windows-attempt-4

Needs rebasing for the msys breakages, needs to override the pre-script because the linux docker images have a cache in the img