[ui] Title bar job start button now observes job submission variables data

[philrenaud]

Resolves #19198

Previously, after stopping a job with variables passed in but no default values, going to the definition page and editing would work fine (as variable literals were already present on the page), but the "start" button would not consider them.

Now they're specifically checked when the job start button is pressed.

Side-effect: utility-ified the json-to-hcl method previously internal to the job editor component.

[github-actions]

Ember Test Audit comparison

	main	6ef27b3	change
passes	1539	1539	0
failures	0	0	0
flaky	0	0	0
duration	11m 03s 740ms	10m 53s 254ms	-10s 486ms

[jrasell]

I've left a minor inline comment; I also think we will need a changelog entry for this.

I tried testing this locally and I get the same error as the linked issue describes. I'm not sure if I am testing this wrong.

[philrenaud]

@jrasell I'm testing with the following jobspec (from your comment in the linked issue, I think):

variable "count" {}

job "example" {
  group "cache" {
    count = var.count
    task "redis" {
      driver = "docker"
      config {
        image = "redis:7"
      }
    }
  }
}

and running with nomad job run -var="count=4" ../nomad-job-specs/bug-empty-variables.nomad.hcl

I'm able to get the "start" button to fire it back up with a count of 4 in the following ways:

• stop, and then immediately restart, via job index butons
• stop, and then refresh, and restart via job index buttons
• stop from elsewhere (cli nomad job stop _____ and open the web UI and start again

In all of these cases, if you happen to go to the definition tab for the job, you should see the count in the variables box:

[jrasell]

LGTM.

Worth noting I think we will also now need the 1.7 backport label as that release branch is now live.