EpicEnv: Overlay Environment Support

A tool that I made a while back that has become a staple in everything I build, I started wanting kustomize-like functionality within environments.

The use case originally was having a simple overlay of S3 environment variables for testing so that they'd use a shared test bucket to provide agents with files, but otherwise we can use a local S3 (garage) when building.

That turned into "overlay environments": you can overlay them on top of each other just like an overlayfs, but for environment variables :)

HN link seems to strip the URL fragments, here's the direct link to the feature: https://github.com/danthegoodman1/EpicEnv/tree/main?tab=read...