Actually update tests to version 3

[jiegillet]

Currently we mark the results.json with a "version": 3, but it's not actually earned.
According to the docs, version 3 means that the test runner can link individual tests to a task, which we don't do.

According to this discussion, it involves updating the version of elm-test-rs.
It will also involve a large PR in exercism/elm to tag all the concept exercise tests to their task.

[jiegillet]

I forgot to mention that the UI for showing the task ID is live now.

[mpizenberg]

I forgot to mention that the UI for showing the task ID is live now

🎉

[mpizenberg]

Really nice to have the UI for tasks :)
My bad, must be my mistake if I updated the version to 3 while this was meant for tests categorized by tasks. Or the version 3 spec changed at some point to include those.
The good thing about still having a relatively small learning track is that it won't be that big to update a few tests files. Usually, tests are already close together for the same task. So it will only be a matter of transforming tests descriptions like this:

-- before
describe "concept"
  [ test "test 1a" <| ...
  , test "test 1b" <| ...
  , test "test 2a" <| ...
  ]

-- after
describe "concept"
  [ describe "1" -- the task id
    [ test "test 1a" <| ...
    , test "test 1b" <| ...
    ]
  , describe "2"
    [ test "test 2a" <| ...
    ]
  ]

[jiegillet]

Closed via #36.