Create example deployment files for BasicAuth

[shaun-nx]

Overview

As a user of NGF
I want to an easy way to setup my Gateway deployment with Basic Authentication
So that I can quickly understand how it works and how to set it up in my environment

Acceptance

• Add example YAML deployment files for BasicAuth using the AuthenticationFilter in nginx-gateway-fabric/examples folder
• Ensure example shows two routes (/tea and /coffee) with an AuthenticationFilter, and one route (/latte) without authentication.