Find sponsor, create and migrate to new Azure subscription

[tomkerkhove]

Now that my OSS sponsorship is gone I need to find a new sponsor, create and migrate to new Azure subscription.

• [x] Find subscription
• [x] https://github.com/promitor/azure-infrastructure/issues/49
• [x] Update legacy Azure Pipelines
• [x] Update GitHub Actions in this repo, if any
• [x] Get passing CI on main

[tomkerkhove]

Subscription 3566a5fa-878c-40fd-ac37-ef0ba0eee29d was created, thank you @amirschw!

[tomkerkhove]

Tracking migration to new infra in https://github.com/promitor/azure-infrastructure/issues/49

[tomkerkhove]

Done!