Webhook Action for Pipelines

### Epic

_No response_

### Description

**As a:** FlowFuse User

**I want to:** be able to push updates to external services

**So that:** I can integrate my FlowFuse stack with additional services like GitHub for backup and version control

Details on the content sent to the Webhook are to be decided, and we could even consider an "in" Webhook too, so that external services can push into a Pipeline from elsewhere to deploy updates to FlowFuse.

### Which customers would this be available to

Team + Enterprise Tiers (EE)

### Acceptance Criteria

- [ ] User can add a "Webhook" action to a Pipeline
- [ ] The Pipeline calls that Webhook when reaching that stage in a Pipeline

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate

### Requested By

- https://app-eu1.hubspot.com/contacts/26586079/record/0-2/13089944531