Support insecure flag on artifact

[amirabbas8]

Hey, I'm so glad this is my first PR to nomad. 🎉

this PR supports an insecure flag for artifact download as described in #19883

The artifact block now supports an insecure flag like the example below. this flag will prevent the go-getter from validating the TLS certificate.

      artifact {
        source        = "https://expired.badssl.com/"
        destination = "local/some-directory"
        insecure     = true
      }

Closes #19883

[hashicorp-cla]

All committers have signed the CLA.

[shoenig]

This is looking great, @amirabbas8! Just the one change around CI testing and I think we should be good.

[shoenig]

Oh you'll also want to run make cl to generate a changelog entry.

[amirabbas8]

@shoenig, Thanks for your review. I have made the changes 🤩

[shoenig]

Hey @amirabbas8 this is very close! Looks like there's a couple failing tests that need to be tweaked. I'm pretty sure in both cases it's just a matter of the test case comparing struct equality and not taking into account the new field. You can ignore the Vercel failures, that's some frontend stuff.

=== FAIL: nomad/structs TestTaskDiff/Artifacts_edited (0.00s)
    diff_test.go:9235: 
        	Error Trace:	/home/runner/work/nomad/nomad/nomad/structs/diff_test.go:9235

and

 === FAIL: client/allocrunner/taskrunner/getter TestParameters_reader (re-run 2) (0.00s)
    assert.go:14: 
        params_test.go:65: expected equality via json marshalling
        ↪ Assertion | differential ↷
          strings.Join({
          	`{"alloc_dir":"/path/to/alloc","artifact_destination":"local/out.`,
          	`txt","artifact_headers":{"X-Nomad-Artifact":["hi"]},"artifact_`,
        + 	`insecure":false,"artifact_`,
          	`mode":2,"artifact_source":"https://example.com/file.txt","decomp`,
          	`ression_limit_file_count":3,"decompression_limit_size":98765,"di`,
          	... // 248 identical bytes
          }, "")

[amirabbas8]

@shoenig, I fixed both test cases, thanks.

[shoenig]

LGTM; thanks @amirabbas8!