vcmi: add before_install.sh

For now, it uses pregenerated deps from my repository, but
should be transitioned to vcmi one after PR is finished

CI/mingw-ubuntu/before_install.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+
+sudo apt-get update
+sudo apt-get install ninja-build mingw-w64 nsis
+sudo update-alternatives --set i686-w64-mingw32-g++ /usr/bin/i686-w64-mingw32-g++-posix
+
+# Workaround for getting new MinGW headers on Ubuntu 22.04.
+# Remove it once MinGW headers version in repository will be 10.0 at least
+curl -O -L http://mirrors.kernel.org/ubuntu/pool/universe/m/mingw-w64/mingw-w64-common_10.0.0-2_all.deb \
+  && sudo dpkg -i mingw-w64-common_10.0.0-2_all.deb;
+curl -O -L http://mirrors.kernel.org/ubuntu/pool/universe/m/mingw-w64/mingw-w64-i686-dev_10.0.0-2_all.deb \
+  && sudo dpkg -i mingw-w64-i686-dev_10.0.0-2_all.deb;
+
+mkdir ~/.conan ; cd ~/.conan
+curl -L "https://github.com/rilian-la-te/vcmi-deps-windows-conan/releases/download/0.0.1/vcmi-deps-windows-conan.tgz" \
+	| tar -xzf -