Create an egress proxy module

[rahearn]

🎫 Addresses issue: #42

closes #42

🛠 Summary of changes

• copy over https://github.com/GSA-TTS/FAC/tree/c827c5bed3562cb2d9949fb85b87694ee19eb77b/terraform/shared/modules/https-proxy implementation to the shared modules
• add an allowports variable to customize the ports caddy is listening on
• add space_name to the cg_space output variables to ease use of both cg_space and egress_proxy modules together

📜 Testing Plan

Implemented and deployed an app using this module: GSA-TTS/continuous-assessment-poc#45

Deploy action: https://github.com/GSA-TTS/continuous-assessment-poc/actions/runs/11277289453

[mogul]

[I feel like my IQ has dropped 100 points since I wrote this... Really proud of the result, just not sure if I'd have the grit to figure it out if I had to today.]

I think there was a Mermaid diagram in the source repo... Am I misremembering? Or is it in the cg-egress-proxy repo? Either way I think it should be included here too. Other than that, these are good additions, and I wouldn't hold up the merge for wont of the diagram.

[rahearn]

I think there was a Mermaid diagram in the source repo...

you're not misremembering, but it is the exact mermaid diagram that's in cg-egress-proxy's README. I'm going to merge this and we'll improve docs/diagrams in due course

[mogul]

Yeah it's the diagram in the original README and the bullets below it