Guidance around using `spk infra generate` secrets from a vault

[NathanielRose]

As an:
Operator

I want:
Documented Integration of how to embed Key Vault into the spk generation pipeline

So that:
Provide guidance on how to leverage KV for handling secrets as environmental variables inside my spk HLD

Describe the solution you'd like:
A section in generation pipeline for spk infra that handles secrets from key vaults as environment variables.

Acceptance Criteria:
Guidance that details:

• Deployment of a key vault within the Generation Pipeline with example secrets
• Calling KV keys from a pipeline in task scripts
• Versioning, permissions, and name mapping of keys

Does this require updates to documentation?:
Yes

[andrebriggs]

@NathanielRose @yradsmikhamthe the updated epic story says that you will be using variable group. My assumption was that a AzDO variable group is backed by AzKV. Are you proposing a different approach?

[yradsmikham]

@andrebriggs The epic does mention variable groups, and in order to keep tasks independent, we have decided that completing #871 should not be blocked by this spike. For now, we are going to use Variable Groups not backed by KV until we fully understand how to incorporate KV appropriately in the pipeline. When we do, we will iterate.