Create job template to build docker image

The manual job build [1] pushed successfully the softwareheritage/maven-index-exporter [2] (build, push, clean).

The remaining limitation is about the account to configure in jenkins.

We are currently using vsellier's api token... (part of the softwareheritage organization in dockerhub). We only have 3 seats in that orga, so we do not have a real place for a bot account for now.

• [1] https://jenkins.softwareheritage.org/job/wip-maven-indexer-exporter/

• [2] https://hub.docker.com/repository/docker/softwareheritage/maven-index-exporter/tags?page=1&ordering=last_updated

Related to swh/infra/sysadm-environment#4105 (closed)

Test Plan

tox

And manual install [1].

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Migrated from D7479 (view on Phabricator)