Support double _ as supported by docker compose

[Rockin-in-a-free-world]

Describe the feature

Support for environment variables with double underscores (__).

The double underscore convention is widely used by Docker Compose and frameworks like ASP.NET Core to represent hierarchical configuration keys in environment variables.

Use case

Users familiar with Docker Compose are used to being allowed to definine environment variables with double underscores to map nested configuration keys. AutoGen currently rejects environment variables containing double underscores, causing deployment failures and preventing the easy transition when migrating existing, working applications.

Proposed solution

The platform’s environment variable parser should recognize and correctly handle double underscores as valid characters in environment variable names and allow parse them to the application runtime.