- Capture exit codes from both golangci-lint runs so a failure in one
  module does not prevent the other from completing or the reports from
  being merged
- In CI, generate a per-module code climate report and merge them into
  gl-code-quality-report.json, as artifacts.reports.codequality only
  accepts a single file

ci: golangci_lint job to use dedicated script

See merge request !508

Merged-by: Matias Alvarez <malvarez@gitlab.com>
Approved-by: Matias Alvarez <malvarez@gitlab.com>
Reviewed-by: GitLab Duo <gitlab-duo@gitlab.com>
Co-authored-by: Luke Hollinda <lhollinda@gitlab.com>

Previously, the CONTRIBUTING.md contained only the DCO/license agreement and
code of conduct; nothing about how to build, test, or contribute code.

This commit adds environment initialization, development instructions,
explains the multi-module pattern, and release process.

chore(CONTRIBUTING.md): developer instructions

See merge request !513

Merged-by: Matias Alvarez <malvarez@gitlab.com>
Approved-by: Matias Alvarez <malvarez@gitlab.com>
Reviewed-by: GitLab Duo <gitlab-duo@gitlab.com>
Reviewed-by: Matias Alvarez <malvarez@gitlab.com>
Co-authored-by: Luke Hollinda <lhollinda@gitlab.com>

feat: update field constants (labkit-spec v1.0)

See merge request !516

Merged-by: Matias Alvarez <malvarez@gitlab.com>
Approved-by: Matias Alvarez <malvarez@gitlab.com>
Co-authored-by: service-platforms-labkit <service-platforms-labkit@gitlab.com>