Migrate the CI pipeline from Travis to Azure Pipeline (#8098)

Fixes #8071 and fixes https://github.com/certbot/certbot/issues/8110.

This PR migrates every job from Travis in Azure Pipeline.

This PR essentially converts the Travis jobs into Azure Pipeline with a complete iso-fonctionality (or I made a mistake). The jobs are added in the relevant existing pipelines (`main`, `nightly`, `advanced-test`, `release`). A global refactoring thanks to the templating system is done to reduce greatly the verbosity of the pipeline descriptions.

A specific feature (not present in Travis) is added: the stage `On_Failure`. Using directly the Mattermost API, it allows to notify pipeline failure in a Mattermost channel with a link to the failed pipelines without the need to authenticate to Microsoft.

See https://github.com/certbot/certbot/pull/8098#issuecomment-649873641 for the post merge actions to do at the end of this work.

snap/local/build.sh

@@ -2,7 +2,7 @@
 # Cross-compile the Certbot snap from local sources for the specified architecture,
 # and install it if this architecture is also the the current machine one.
 # This script is designed for CI tests purpose.
-# Usage: build_and_install.sh [amd64,arm64,armhf]
+# Usage: build.sh [amd64,arm64,armhf]
 set -ex
 
 SNAP_ARCH=$1
@@ -40,7 +40,3 @@ docker run \
   -e "PIP_EXTRA_INDEX_URL=http://localhost:8080" \
   "adferrand/snapcraft:${DOCKER_ARCH}-stable" \
   snapcraft
-
-if [[ "$(arch)" == "${QEMU_ARCH}" ]]; then
-    sudo snap install --dangerous --classic *.snap
-fi