Enable exporting variables across jobs on Azure Pipelines

[ravenpride]

This PR tells Azure Pipelines to export GitVersion variables across jobs. Without it the variables are only usable from within the same job. For more information on variables at Azure Pipelines, please see the official documentation.

[asbjornu]

Thank you for your contributions, @ravenpride! 🙏

[jetersen]

Hmm testing this out I can't even get variables to go to next step:
https://dev.azure.com/3ShapeOld/Docker-CI/_build/results?buildId=1227&view=logs&j=b457fee1-24b5-5b05-276f-95f55538c81f&t=b62f2c6f-5e7b-585f-7ef6-e0598356bd9d&l=89

https://github.com/3shape/docker-ci/blob/azure-pipelines/azure-pipelines.yml

[ravenpride]

Within a job, you do not need to specify the name of the task. The following should suffice:

      env:
        GitVersion_Version: $(GitVersion.MajorMinorPatch)
        GitVersion_PreReleaseTagWithDash: $(GitVersion.PreReleaseTagWithDash)

If you need to pass the variables across jobs (within the same stage), it gets a bit tricky. Then you need to declare a dependency to the job that contains the task publishing the desired output variables and the output variables in a more elaborate way:

- job:
  dependsOn: <name-of-the-job-publishing-the-variables>
  env:
    GitVersion_Version: $[ dependencies.<name-of-the-job-publishing-the-variables>.outputs['<name-of-the-task/script-publishing-the-variables>.GitVersion.Version'] ]
    GitVersion_PreReleaseTagWithDash: $[ dependencies.<name-of-your-task-publishing-the-variables>.outputs['<name-of-the-task/script-publishing-the-variables>.GitVersion.PreReleaseTagWithDash'] ]

[jetersen]

Thanks figured it out after reading the docs several time 😄