feat: ability to set resource labels from a workflow

[kirederik]

As a platform owner (and maybe promise author)
I want to update my resource with some labels or annotations
So that I can integrate with my systems

Context

We allow resource status to be updated from the pipeline, but provide no mechanism for labels or annotations. Allowing those to be set is useful for our users.

Acceptance

Scenario: labels from the workflow
Given a stage that uses the labelling feature
When I apply the resource request and the pipeline completes
Then the resource includes the dynamically generated labels

Scenario: GO SDK
Given I'm building stages with the Go sdk
When I want to apply labels to my resource
Then I can use a helper function

Scenario: Python SDK
Given I'm building stages with the Python sdk
When I want to apply labels to my resource
Then I can use a helper function

Tasks

• Update docs