[ECS] [request]: Show ValueFrom environment variables in console

**Tell us about your request**
Show _ValueFrom_ environment variable names in the console under _Cluster_ -> _Task_ -> _Container_ -> _Details_.

**Which service(s) is this request for?**
ECS web console.

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
_ValueFrom_ environment variables are missing from the console under Cluster -> Task -> _Container_ -> Details.
Only _Value_ environment variables are shown here which is a bit confusing.

**Are you currently working around this issue?**
I have to open the task definition and look there.