Create arm64 image for secretgen-controller

[jorgemoralespou]

Describe the problem/challenge you have
Currently, secretgen-controller cannot run on an ARM64 host, as there is no image[0].

Could we switch to doing multi-arch builds and produce arm64 alongside amd64?

Related issue for kapp-controller: carvel-dev/kapp-controller#573

This is needed for Tanzu Community Edition

[joe-kimmel-vmw]

Thanks @jorgemoralespou - is there a timetable for this ask?

[jorgemoralespou]

This is related to a bigger epic in tanzu community edition. Currently engineering have built their own image, so the sooner, the better, as with kapp-controller.