This provides changes and new commands used for release.

Adjust other references to the old 'gitblit' organisation on Github to
point to the new 'gitblit-org' organisation.

Leave the artefact until after the container has been built and tested.
In case the test fails the artefact can be still downloaded to analyse
what might have caused the container build or test to fail.

The Github 'checkout' action was updated from v1 to v3. But the behaviour
changed between the two which broke this workflow.
The old action would clone other repositories not into the workspace
but parallel to the workspace. The new version does every clone/checkout
relative to the workspace. That means that where previously the
gitblit-docker repository would be cloned in parallel to the workspace
which is gitblit/gitblit, it is now cloned into the gitblit/gitblit
directory path.

So remove all the references to `../gitblit-docker`. The files are in
the current directory now.

The `set-output` command was deprecated. The new way to set an output
parameter for a step is to echo to the file stored in `$GITHUB_OUTPUT`

Versions are updated for various actions that have a new version which
uses NodeJS 16.

One action has no updated version available yet:
`e1himself/goss-installation-action`
But an issue exists mentioning that it needs an update.

The workflow runs started issuing warnings because NodeJS 12 was
deprecated. Actions need to get updated to newer versions that use
NodeJS 16. This commit updates the `actions/checkout` and the
`actions/setup-java` actions to the latest version in the workflow that
builds on every push.

The new setup-java action requires the distribution to be specified,
since multiple JDK distributions are supported now. We chose Eclipse's
Temurin here which is the successor to AdoptOpenJDK, which we use for
development.

Build pull requests, just like we build on every push.

For some reason the secret gate doesn't work and the main Gitblit
repo also attempts to deploy the nightly to Docker which must fail.

Enable a switch for manual workflow triggering that overrides the check
if a new commits were made since the last build. If the input is set to
'true', a new build is run even when no new commits are present.

This is mainly so that changes to the gitblit-docker repo can be included
in builds. This could also be automated in the workflow, if need be.

Set the ignored branches pattern to `release*` for the normal ci workflow.

Add a job to run a build with Java 7.
The job currently only runs on Linux.
In order to run on Java 7, an old Ant version is downloaded and
installed. We use moxie+ant for this, so we build with moxie.

Currently that is Ubuntu 18.04 and Windows Server 2019.
https://help.github.com/en/actions/automating-your-workflow-with-github-actions/virtual-environments-for-github-hosted-runners

We cannot build with Ant on GitHub since the provided Ant
version does not run on Java 7.