Add FIPS NGINX Ingress Controller image

Add Dockerfile to build a FIPS-compatible distribution of the NGINX Ingress Controller image, along with a Make target to handle the build process.

Summary

• Builds an image containing the binaries built with FIPS-compatible Go compiler
  • registry.gitlab.com/gitlab-org/cloud-native/charts/gitlab-ingress-nginx/binaries:$TAG-fips
  • It is built this way to make it as easy as possible to replicate a FIPS-comaptible build environment, whereas the traditional binaries are just built locally (which, in CI, is just a docker-based image)
• Builds an image for the NGINX Ingress Controller using the FIPS-compatible binaries built above
  • registry.gitlab.com/gitlab-org/cloud-native/charts/gitlab-ingress-nginx/controller:$TAG-fips

Changelog: added

Closes #2 (closed)