GitAuto: Listen jira issue webhook event on this Jira Forge App

[gitauto-ai]

Resolves #17

What is the feature

Add functionality to listen to Jira issue webhook events within the Jira Forge App.

Where / How to code and why

• src/webhook.js: Implement a webhook handler to process incoming Jira issue events. This will enable the Forge App to respond to various issue lifecycle events such as creation, updates, and transitions.

• manifest.yml: Update the app manifest to include webhook subscriptions for the relevant Jira issue events. This ensures that Jira sends the appropriate events to the Forge App.

• src/index.js: Register the webhook handler to ensure it is correctly incorporated into the app's routing and processing logic.

These changes adhere to modern best practices for extending Jira Forge Apps, ensuring robust and scalable integration with Jira's issue tracking system.

Anything the issuer needs to do

• Register the webhook in Jira to point to the Forge App's webhook endpoint.

Test these changes locally

git fetch origin
git checkout gitauto/issue-17-20241224-000734
git pull origin gitauto/issue-17-20241224-000734