Config: support .env.testing and .env.e2e files

[LoicPoullain]

Issue

Currently, Foal's configuration system supports environment variables, the .env file and JSON and YAML files in the config/ directory. In some situations, we may also want to have another uncommitted file .env.testing to store db credentials during testing.

Solution

Support .env.{NODE_ENV} files

[yaaminu]

@LoicPoullain I'm struggling to understand the utility of this since there's already a comprehensive way for adding configurations to a foal app. I suggest we stick to the existing approach and add a new test.{yml|json} configuration file for test environments.

[LoicPoullain]

This will allow us to split sensitive information and simple settings in two different files if we want to (one committed and the other not). There is no obligation to use this approach and we will still be able to only use test.{yml|json} files if we prefer.

Another use case can be to start the app with our production DB. For example, by adding a .env.production file with the credentials and running the command NODE_ENV=production npm run start.

This is not a priority though. I'll remove it from August release to focus on social auth.

[LoicPoullain]

Resolved in v2