Add: [AzurePipeline] introducing a release pipeline

This release pipeline creates all the official release binaries,
and publishes them as artifacts. Currently it can only produce
nightlies and custom builds; stable/testing release binaries are
untested.

This commit also splits up the pipeline in small bits, to both
improve readability, and to share code with the CI pipeline where
possible.

findversion.sh

@@ -74,8 +74,6 @@ if [ -d "$ROOT_DIR/.git" ]; then
 
 	if [ -n "$TAG" ]; then
 		VERSION="${TAG}"
-	elif [ "${BRANCH}" = "master" ]; then
-		VERSION="${ISODATE}-g${SHORTHASH}"
 	else
 		VERSION="${ISODATE}-${BRANCH}-g${SHORTHASH}"
 	fi