Allow configuration of environment variables for the runtime environment

[nuest]

id: b9b0099e-9f8d-4a33-8acf-cb0c062efaec
version: 1
execution:
  environment:
    - TZ=CET

The only option for run is environment to set environment variables inside containers as defined in docker-compose.
Environment variables are defined as a list of strings.
Key and value are separated by =.

The environment variables SHOULD be used to fix settings out of control of the contained code that can hinder successful ERC checking, e.g. by setting a time zone to avoid issues during checking.