[policy, no patch] Image optimization performance core gate

Adding the template used by the core gates.

What is the criteria to use?

The idea here was to ensure that new core assets, like logos, icons etc. are optimized. So it is something like a step to ensure that's not forgotten. I don't think we can specify specific tooling since things change all the time.

Well, OTOH, I think we have to specify specific tooling and then update the gate as standards evolve; otherwise we can't really apply the gate.