Support Postman Environments

**System information**

- Version of Services: 2.0.0-aplha
- Are you willing to contribute it (Yes/No): Yes

**Describe the feature and the current behavior/state.**

Currently the postman collection uses collection variables, but that means that if you want to interact with a different node, you need to change the referenced variables in every request you want to use. With an env, you could have an env for each node, so you just switch env when you want to interact with the other node, and all the requests will fall in line

**Will this change the current API? How?**

No

**Who will benefit with this feature?**

Make the postman collection easier to use

**Miscellaneous Information**

No source file or test is named in the issue. Start by locating the Postman collection and its current collection-variable definitions, then check how requests reference the node values. Done means users can select an environment for each node without editing variables in individual requests, while the API remains unchanged.

Written by the indexing model from the issue text.