Multi-Arch Support for oci-registry builds and CI

[Jdubrick]

Please specify the area for this PR
Updating CI to support multi-arch image building

What does does this PR do / why we need it:
This PR contains the following changes:

• Updated build.sh script to allow for easy building of different architecture images, by default linux/amd64 will be built with no arguments passed
• Updated oci-registry/README.md to reflect the additional functionality of build.sh
• Updated ci.yaml to include QEMU for Docker so that the workflow can build linux/arm64 images
• Updated ci.yaml to test the builds for both linux/amd64 and linux/arm64 oci-registry images
• Created build-multi-arch.sh to enable multi-arch building and pushing for the oci-registry images. This by default will use Docker as github workflows supports that, however, it also allows for podman to be used if we ever switch. This script handles the building of both linux/amd64 and linux/arm64 images, the creation of the image manifest, and the pushing of all 3 items to quay.io/devfile/oci-registry. The architecture specific images will be tagged amd64 and arm64 for their respective images, and the manifest will be tagged next. Users should see no change in their workflow for pulling the quay.io/devfile/oci-registry:next image, it will pull the proper architecture for the OS pulling.
• Updated pushimage-next.yaml to include QEMU for Docker as well as run the multi-arch script.

Which issue(s) this PR fixes:

fixes devfile/api#1546

PR acceptance criteria:

• Test Coverage
  • Are your changes sufficiently tested, and are any applicable test cases added or updated to cover your changes?

Documentation (WIP)

• Does the REST API doc need to be updated with your changes?
• Does the registry library doc need to be updated with your changes?

How to test changes / Special notes to the reviewer:

[thepetk]

Tested locally the scripts and left some comments. One question in general I have is for the manifests and their importance on the script. Mostly because while I've seen this feature in the pas is the first time I see it in action :D

[thepetk]

/lgtm tested the scripts locally using my personal quay.io account and they were working correctly.

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Jdubrick, thepetk

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