tools/version-bumper: support for detecting older/unused API Versions of Resource Manager APIs

[tombuildsstuff]

At this point in time the version-bumper tool automatically detects new (Stable) API Versions of Resource Manager APIs as they become available - meaning that a PR is sent to propose adding support for this new API Version (example).

Similarly, when a new API Version is added to Pandora and makes its way through hashicorp/go-azure-sdk - there’s automation which updates hashicorp/terraform-provider-azurerm to use this new API Version, assuming the payloads are compatible (and thus the provider compiles).

As such whilst we’re currently adding new API versions - we’re needing to go through and manually clean up the older ones.

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Rather than doing this by hand, we could update the Version Bumper so that it detects which API Versions are currently used in both:

• hashicorp/terraform-provider-azurerm
• hashicorp/packer-plugin-azure
• tombuildsstuff/azurerm-dalek

And if these aren’t used (and are older than what’s currently vendored) - we could remove these from the list of supported API versions.

This would mean that Pandora would be able to both detect new API Versions as they become available - and remove older API Versions as they’re no longer needed - removing this overhead.

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Whilst this is a fairly low priority feature request, some APIs release more frequently than others - meaning that we end up keeping older versions around. That’s less of an issue for smaller services, but more of an issue for the larger ones - particularly RecoveryServices (for which we currently import 10 different versions), Network (for which we currently import 4 different versions) and Compute (for which we currently import 7 different versions).

In some cases (e.g. Compute) not all functionality is available in all API versions, but that requires context/manual investigation to ascertain/know which API Versions are fine to remove - as such whilst this is a low priority feature request, there’s benefit to having this automated.