Added a demand checker for Azure Pipelines

[Eldarrin]

Added a parameter to the metadata so that you can specify a parent template which must be the ADO agent name of the offline agent.

Job now compares the template name to determine if it is matched to a potential agent

Issues: If more than one agent can fulfil the job, multiple jobs can be instantiated as they decide independently that they are able to fulfil.

Docs: kedacore/keda-docs#685

Andy

Checklist

• Commits are signed with Developer Certificate of Origin (DCO - learn more)
• Tests have been added
• A PR is opened to update our Helm chart (repo) (if applicable, ie. when deployment manifests are modified)
• A PR is opened to update the documentation on (repo) (if applicable)
• Changelog has been updated and is aligned with our changelog requirements

Relates to #2328

[zroubalik]

Would you mind addind some tests?

[zroubalik]

@Eldarrin please check you PR, seems like there is something broken and there are included changes from another PRs.

[Eldarrin]

Seems like my fork is corrupted with a previous merge. May be best if I kill the fork, You close the PR. I'll open a new PR with a clean fork and reference this one.