Dvc: make dvc repro STAGE running all parametrized stages

[johnnychen94]

stages:
  build:
    foreach:
      - 15
      - 25
      - 35
    do:
      cmd: echo ${item}

jc@mathai3:~/Downloads/dvc_test$ dvc repro build@15
Running callback stage 'build@15' with command:
    echo 15
15
Use `dvc push` to send your updates to remote storage.

The following version doesn't work, even though build is defined in stages section.

jc@mathai3:~/Downloads/dvc_test$ dvc repro build
ERROR: "Stage 'build' not found inside 'dvc.yaml' file"

I wish we could make it equivalent to

for item in 15 25 35; do
    dvc repro build@$item
done

Furthermore, depends on whether there's a lock, multiple stages can be run in parallel.

[skshetry]

Hi, @johnnychen94. Glad to see an issue for the parameterization (and, seeing someone using it :smile:). I am working on this feature and will be implemented around the pre-release (which might be backwards-incompatible).

[skshetry]

@johnnychen94, I have created #4976 to implement this. Your feedback would be greatly appreciated.

[johnnychen94]

It's not closed related so I put my thoughts in #4979 on what I'm expecting.

---

I'm impressed with how fast you DVC guys respond and the schedule you've made. Definitely something I should introduce to the Julia community 😆