publish images with microarch levels

[sozercan]

Describe the solution you'd like
docker allows us to build and publish images that can target specific microarch levels, such as linux/amd64/v2, and linux/amd64/v3. these align with https://en.wikipedia.org/wiki/X86-64#Microarchitecture_levels

today, we publish with linux/amd64 which might be leaving perf on the table

first, we should measure if there is any perf impact using optimized builds. we already have benchmarks so we can run those.
if there are meaningful benefits, publish images with diff arch levels. runtime should auto feature detect and pick the suitable one so this should be invisible to users, while they get the benefit of increased perf

Anything else you would like to add:
GOAMD64: https://tip.golang.org/wiki/MinimumRequirements#amd64

Environment:

• Gatekeeper version:
• Kubernetes version: (use kubectl version):