feature: Improve testing experience for webhook transforms

[minitriga]

Component

infrahubctl CLI

Describe the Feature Request

Testing transforms that are used with webhooks is currently impractical because the data structure passed to the transform differs significantly between testing and production execution.

Describe the Use Case

When testing with infrahubctl transform:

• The transform's query attribute is executed via GraphQL
• The transform receives query results (structured as GraphQL response data)

When running in production (webhook triggered):

• The transform's query attribute is required but completely ignored
• The transform receives event payload data directly with structure:
  {
  "data": {"kind": "...", "action": "...", "node_id": "..."},
  "id": "event-uuid",
  "event": "infrahub.node.updated",
  "branch": None,
  "account_id": "account-uuid",
  "occured_at": "2025-03-13T16:31:14.566032+00:00"
  }

Why This Is a Problem

1. Data structure mismatch: A transform that works correctly in testing will
   fail in production because it expects query-structured data but receives
   event-structured data
2. No way to test with event data: There's no CLI command or testing mechanism
   to pass mock event payloads to a transform
3. Confusing API: The query attribute is required on webhook transforms but
   serves no purpose
4. False confidence: Passing tests don't guarantee the transform will work
   when triggered by actual webhooks

Additional Information

No response

[ogenstad]

There's some overlap between this and opsmill/infrahub#1847