TUN-4771: Upload deb, rpm and msi packages to github

- cfsetup now has a build command `github-release-pkgs` to release linux
   and msi packages to github.
 - github_message.py now has an option to upload all assets in a provided
   directory.

cfsetup.yaml

@@ -27,10 +27,35 @@ stretch: &stretch
       - libmsi-dev
       - libgcab-dev
     pre-cache:
+      # TODO: https://jira.cfops.it/browse/TUN-4792 Replace this wixl with the official one once msitools supports
+      # environment.
       - wget https://github.com/sudarshan-reddy/msitools/releases/download/v0.101b/wixl -P /usr/local/bin
       - chmod a+x /usr/local/bin/wixl
     post-cache:
       - ./build-packages.sh
+  github-release-pkgs:
+    build_dir: *build_dir
+    builddeps:
+      - *pinned_go_fips
+      - build-essential
+      - fakeroot
+      - rubygem-fpm
+      - rpm
+      - wget
+      # libmsi and libgcab are libraries the wixl binary depends on.
+      - libmsi-dev
+      - libgcab-dev
+      - python3-setuptools
+      - python3-pip
+    pre-cache:
+      - wget https://github.com/sudarshan-reddy/msitools/releases/download/v0.101b/wixl -P /usr/local/bin
+      - chmod a+x /usr/local/bin/wixl
+      - pip3 install pygithub
+    post-cache:
+      # build all packages and move them to /cfsetup/built_artifacts
+      - ./build-packages.sh
+      # release the packages built and moved to /cfsetup/built_artifacts
+      - make github-release-built-pkgs
   build-deb:
     build_dir: *build_dir
     builddeps: &build_deb_deps