Also build for arm64

[jksolbakken]

Summary:
Builds Docker images also for ARM. Improves developer experience on newer Macs with ARM CPU (Mx)
Adds necessary changes to the affected GitHub workflows

Description for the changelog:
add build for arm64 docker image in GitHub workflows

Other info:
The extra build time should be bearable, if not the builds for each arch can be run in parallel using a matrix.

[jgadsden]

superb, many thanks @jksolbakken

[jksolbakken]

The build fails because of missing secrets for login to Docker Hub. Maybe remove the login step and do not push from the PR workflow?

[jgadsden]

possible - although the e2e and zap stages may fail if this is done? Looking at it again the workflow should be changed anyway to cache the docker image so that e2e and zap work OK
if you want to experiment please go ahead, I will give you some permissions to run the workflows @jksolbakken

[jksolbakken]

I will update this PR to run the build step before the login for PRs. That way we can determine if the image build itself works without the need for elevated privs. The other steps should work as before when you merge. Secrets are not available if the workflow was caused by an external PR.

[jksolbakken]

No, wait that won't work. I'll come up with a solution.

[jgadsden]

thanks agin @jksolbakken , and will go ahead and merge