feat(dotenv-flow-webpack): add options.pattern for customizing .env* files' naming convention

[kerimdzhanov]

Summary

This PR introduces a new configuration option pattern. It allows users to define a custom naming convention for .env* files that dotenv-flow-webpack will read.

The default value for the pattern option is ".env[.node_env][.local]" which is fully backward-compatible with the current dotenv-flow's naming convention.

Description

options.pattern allows you to change the default .env* files' naming convention if you want to have a specific file naming structure for maintaining your environment variables' files.

Default Value

The default value ".env[.node_env][.local]" makes dotenv-flow-webpack look up and load the following files in order:

1. .env
2. .env.local
3. .env.${NODE_ENV}
4. .env.${NODE_ENV}.local

For example, when the proess.env.NODE_ENV (or options.node_env) is set to "development", dotenv-flow-webpack will be looking for and parsing (if found) the following files:

1. .env
2. .env.local
3. .env.development
4. .env.development.local

Custom Patterns

Here are a couple of examples of customizing the .env* files naming convention:

For example, if you set the pattern to ".env/[local/]env[.node_env]", dotenv-flow-webpack will look for these files instead:

1. .env/env
2. .env/local/env
3. .env/env.development
4. .env/local/env.development

… or if you set the pattern to ".env/[.node_env/].env[.node_env][.local]", the plugin will try to find and parse:

1. .env/.env
2. .env/.env.local
3. .env/development/.env.development
4. .env/development/.env.development.local

› Please refer to dotenv-flow.listFiles(options) to learn more.