This commit adds the last bits needed to have a working
CI job of cerbero using mingw and msvc17 toolchain.
It adds a new stage to the docker image that mirrors
the setup of the cerbero fedora docker build, and
tweaks the cerbero_setup script run by jobs with
a couple windows specific fixes.
Close#39
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-ci/-/merge_requests/334>
Its hard to manage ever growing bash scripts in yaml, and
its even harder to run them locally to reproduce the environment.
This is essentially a copy-paste of the scripts, to make review
easier. We can refactor later.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-ci/-/merge_requests/329>