Version or additional column(s) in environment list

Description

In order to get better overview on what and which release is currently on an environment, it would be grateful having an additional column in the environment page with the deployed version.

Proposal

Add possibility to add additional element to the environment element in .gitlab-ci.yml like:

deploy:
  stage: deploy
  environment:
    name: dev
    version: $MY_VERSION

or

deploy:
  stage: deploy
  environment:
    name: dev
    metadata: 
     myversion1: $MY_VERSION
     veryuseful: $VERYUSEFUL_INFO

Links / references

Documentation blurb

Overview

Use cases

Having fast overview of which version in which environment currently is deployed:

screen

Maybe would this should also be displayed it would be also nice having that in the pipeline screen, when hovering of the a deploy stage.

Feature checklist

Make sure these are completed before closing the issue, with a link to the relevant commit.