Fix/mirror cicd multiarch (#786)

* Pushing multi arch images to Nexus and Harbor

* Create manifest list, push it and sign it

* Add build dependency to manifest creation

* moving harbor destination to input variable for workflow_dipatch

* Make job titles more speaking

* Adding cosign install to manifest list creation

* Using digest for manifest creation

* Making shellcheck happy

* Making shellcheck happy 2

* Making shellcheck happy 3

* Hardcoding harbor dest like nexus

* Hinting how to nest structs

Author: Maleware

.github/workflows/mirror.yaml

@@ -7,7 +7,7 @@
           description: 'Location of the source image (example: registry.k8s.io/git-sync/git-sync:v3.6.4)'
           required: true
         dst:
-          description: 'Name and tag of the destination image (example: git-sync:v3.6.4)'
+          description: 'Name and tag of the destination image (example: git-sync:v3.6.4) ( nested structs are done with e.g. sig-storage/csi-provisioner:2.10.1 )'
           required: true
 
   env: