feat: Add several demos

[fabriziofiorucci]

Proposed changes

Added

• NGINX Advanced Healthcheck
• NGINX API Steering
• NGINX Docker Image Builder
• NGINX Multicloud Gateway
• NGINX NIM Docker
• NGINX SOAP REST

Checklist

Before creating a PR, run through this checklist and mark each as complete:

• I have read the contributing guidelines.
• I have signed the F5 Contributor License Agreement (CLA).
• If applicable, I have added tests that prove my fix is effective or that my feature works.
• If applicable, I have checked that any relevant tests pass after adding my changes.
• I have updated any relevant documentation (README.md and/or CHANGELOG.md).

[Copilot]

PR Overview

This PR adds several demo implementations for various NGINX advanced features. Key changes include:

• Implementation of NGINX API Steering logic with JSON payload transformations.
• Addition of demo Flask applications for the API server and backend service.
• Inclusion of Docker Compose and Kubernetes configuration files for deployment.

Reviewed Changes

File	Description
NGINX-API-Steering/nginx/steering.js	New API steering logic with subrequest handling and JSON updates.
NGINX-API-Steering/apiserver/apiserver.py	Demo Flask API server implementation.
NGINX-API-Steering/backend/backend.py	Demo Flask backend exposing rule data.
NGINX-API-Steering/docker-compose.yaml	Docker Compose configuration for multi-container deployment.
NGINX-API-Steering/kubernetes.yaml	Kubernetes deployment configuration for the demos.

Copilot reviewed 101 out of 101 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (4)

NGINX-API-Steering/nginx/steering.js:24

• Consider verifying the type of 'enabled' rather than comparing to the string 'false'. If the expected value is a boolean, use a boolean check (e.g. if (!body.rule.enabled)).

if (body.rule.enabled == 'false') {

NGINX-API-Steering/nginx/steering.js:42

• Declare the variable 'requestBody' in an outer scope before the if block so it is defined when used in the subsequent subrequest call.

if (r.requestText) {

NGINX-API-Steering/nginx/steering.js:135

• [nitpick] The comment indicates a string is returned, but the function returns a JSON object. Update the comment to accurately reflect the return type.

// Return the updated JSON object as a string

NGINX-API-Steering/apiserver/apiserver.py:25

• Store the result of request.get_json() in a variable to avoid calling the method twice, which improves readability and potential performance.

payload = request.get_json() if request.get_json() != None else ''