[Epic] Tracking issue for updating our release pipelines to sign artifacts.

[100mik]

This issue tracks similar ones in specific repositories that capture the work required for the making changes recommended by this proposal for signing Carvel artefacts by @ThomasVitale.

• https://github.com/carvel-dev/ytt/issues/873
• https://github.com/carvel-dev/kapp/issues/827
• https://github.com/carvel-dev/kbld/issues/417
• https://github.com/carvel-dev/vendir/issues/297
• https://github.com/carvel-dev/imgpkg/issues/583
• https://github.com/carvel-dev/kapp-controller/issues/1341
• https://github.com/carvel-dev/kapp-controller/issues/1343
• https://github.com/carvel-dev/secretgen-controller/issues/496

This issue can be closed out upon completion of the ones linked in it.

[github-actions[bot]]

This issue is being marked as stale due to a long period of inactivity and will be closed in 5 days if there is no response.

[praveenrewar]

All artifacts are now signed.