(gdk): allow environment variables substitition in gdk-config.json

[statefb]

Feature Description Allowing environment variables substitution into recipe file.

Use Case

• When Greengrass component developers are working on their respective accounts, there are cases where they want to override the values in the recipe.yaml or recipe.json committed to Git with their own environment variables.
• They also want to avoid committing any secret values to Git and instead inject them from environment variables.
• It would be even better if they could load these values from a .env file. Each individual can add their own .env file to the .gitignore and follow a development process accordingly.

Proposed Solution

• Substitute env variables before zip or build component
• Using or implementing template engine mechanism such as: Emrichen – Template engine for YAML & JSON

Other N/A

• [x] :wave: I may be able to implement this feature request
• [ ] :warning: This feature might incur a breaking change