Add terraform scripts to build nginx image

[aledbf]

What this PR does / why we need it:

This PD adds the required automation to build and publish the NGINX and ingress controller docker images using an AWS spot instance using terraform.

Why?

• building in a particular workstation is not a good practice
• anyone with write access to quay.io can build the images
• building the NGINX images for the three platforms, amd64, arm, and arm64 take up to two hours.

Until now I was using the same approach but doing all this manually, using this gist https://gist.github.com/aledbf/e897c01f9fa285fccac04f8fd0e1047a as base

this is one of the tasks required before #4404

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #

Special notes for your reviewer:

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aledbf

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• OWNERS [aledbf]

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