fix(DMVP-9224): support templates in hostname(and not only) variables of gateway api common htproute/istio-envoyfilter/istio-authorizationpolicy configs

[mrdntgrn]

Summary

Adds DMVP-9224 support for templated values in Gateway API route and Istio policy/filter configuration fields, with updated chart docs, runnable examples, and full Speckit planning artifacts for implementation traceability.

Key Changes

• Added Helm tpl rendering support for httpRoutes[].hostnames in charts/gateway-api/templates/httproute.yaml.
• Added Helm tpl rendering support for AuthorizationPolicy rules in charts/gateway-api/templates/istio/authorizationpolicy.yaml.
• Added Helm tpl rendering support for EnvoyFilter configPatches in charts/gateway-api/templates/istio/envoyfilter.yaml.
• Bumped gateway-api chart version in charts/gateway-api/Chart.yaml.
• Updated charts/gateway-api/README.md to document templating support for hostname/rules/config patches.
• Updated examples/gateway-api/with-istio-envoyfilter-direct-response.yaml with templated usage additions.
• Added new example examples/gateway-api/with-template-hostname.yaml to demonstrate template-driven hostnames.
• Added feature specification at specs/011-gateway-tpl-support/spec.md.
• Added implementation plan at specs/011-gateway-tpl-support/plan.md.
• Added task breakdown at specs/011-gateway-tpl-support/tasks.md.
• Added supporting artifacts: research.md, data-model.md, contracts/render-contract.md, quickstart.md.
• Added requirements checklist at specs/011-gateway-tpl-support/checklists/requirements.md.

[what-the-diff]

Woohoo! 🎉 What an exciting update we have here! We've done some significant heavy lifting to bring you a great set of enrichments!

Chart Embellishments: From 0.1.5 to 0.1.6 🚀

With this update, we've upgraded our chart version from 0.1.5 to 0.1.6. This may seem like a tiny step ...but in the grand scheme of things, it's a giant leap towards offering you better functionality!

Reading Made Easy With Template Expressions 📝

The README has been updated to detail a fantastic new feature! We now support templated expressions -- a fancy term for a neat trick which lets you customize fields like httpRoutes[].hostnames more efficiently. It's all thanks to Helm tpl.

Major Template Overhauls 🎨

We've sprinkled our magic tpl dust over several templates including httproute.yaml, authorizationpolicy.yaml, and envoyfilter.yaml. These updates allow for more dynamic rendering of details such as hostnames, policy rules and config patches.

A Peek Behind the Scenes With New Example Files 🍿

Wonder how to make most out of these changes? Check out our new example file demonstrating template usage. It's like a behind-the-scenes tour, guaranteed to help you get to grips with httpRoutes and directResponse.

Documenting Our Journey 🌎

We've created a plethora of specification documents and checklists for you. These will help you verify the templating support including render contracts and data models. Plus, we've assembled the research findings and game plan for the templating feature.

Guiding You Through the Maze 🧭

We've included steps and rapid start instructions to navigate the new Helm templating capabilities. Because we believe that the first step is always the hardest, and we're here to make it as smooth as possible.

Even More Exciting Work 🔍

Feature Specifications 📘

In the spec.md file, we've gone real specific, detailing user stories, acceptance criteria, edge cases, and functional requirements. We've also detailed what success looks like for the cool new Gateway API template (tpl) support.

Task by Task, Brick by Brick, We've Built a Wall 🧱

In the tasks.md file, we've meticulously outlined the implementation phases, tasks, tests, and dependencies related to the new features. It's a snapshot of how we're building new functionalities that enhance rendering while preserving the existing static behavior for you.

User Stories and Priorities 📚

These are the stories of the folks using our product. Here you'll find stories of users with different priorities and how we've planned to give everyone a delightful experience by enhancing templated rendering.

Documentation and Examples Galore 🌟

We can't emphasize enough how committed we are to ensuring you understand these new enhancements. We've made it a point to provide both detailed documentation and working examples. So, you can learn to utilize the new templating capability without any hiccup.

Transforming something complex into a natural user-friendly experience... That's what we're all about! Let's continue to create fantastic things together! 🚀😃