resolve service environment "just in time"

[ndeloof]

What I did
resolve service environment just before container get created
doing so, a provider service depends on can inject variables, used for interpolation
example usage:

services: Docker Desktop   o View Config   w Enable Watch
  test:
    image: ...
    environment:
      - OPENAI_API_BASE=${LLM_URL}
    depends_on:
      - llm

  llm:
    provider:
      type: model
      options:
        model: llama123

note this is just a draft, need to play with this branch to better understand the possible side effects

Related issue
requires compose-spec/compose-go#797

(not mandatory) A picture of a cute animal, if possible in relation to what you did