Fix GHA trigger for Windows images

[yosifkit]

This fixes the GHA trigger job to account for the data models changes in #27. Also moves the jq from the Jenkinsfile to a jq module for easier debugging.

main change:

-[ .build.resolvedParents[].manifest.desc.platform? | select(has("os.version")) | ."os.version" ][0] // ""
+[ .build.resolvedParents[].manifests[].platform? | select(has("os.version")) | ."os.version" ][0] // ""

$ jq -L. 'include "meta";  first( .[] | select( .build.arch == "amd64" ) )' ../meta/builds.json | jq 'include "jenkins"; gha_payload'
{
  "ref": "subset",
  "inputs": {
    "buildId": "7cc7df30afc4b4d52dd16d4b6d1335d9c913ae59b5533350f5debf8c07e4fc31",
    "bashbrewArch": "amd64",
    "firstTag": "bash:devel-20240304"
  }
}
$ jq -L. 'include "meta";  first( .[] | select( needs_build and .build.arch == "windows-amd64" ) )' ../meta/builds.json | jq 'include "jenkins"; gha_payload'
{
  "ref": "subset",
  "inputs": {
    "buildId": "3e083562fa8d67d9a48c3d94a06c65dfd5177c4593334cf1b898d4cbafffc71f",
    "bashbrewArch": "windows-amd64",
    "firstTag": "docker:26.0.0-rc1-windowsservercore-ltsc2022",
    "windowsVersion": "2022"
  }
}

Current failure is GHA jobs just failing to start by waiting for a non-existent windows machine:

Requested labels: windows-
Job defined at: docker-library/meta/.github/workflows/build.yml@refs/heads/subset
Waiting for a runner to pick up this job...