Add rate limiting for public env

Created by: chess-knight

Limit is applied in front of Harbor - on the ingress-nginx

Fixes #38 (closed)

As we can see DockerHub overall limit and Quay.io rate limit there is thousands of requests per minute respectively tens of requests per second. For the Project Quay, nginx limits are mentioned here. Its about 50r/s based on location.

This harbor instance is a little less used, so 25 limit per second seems to be fine here. This limit is also only a local limit, in the case of n ingress controllers pods, limit = limit * n. In the edge case, we are also fine with docker theoretical max layer depth limit, which is 125 because burts rate limit is set to limit-rps * 5(multiplier can be changed). So in this burst case, we are able to process 1 + 25 * 5 requests within 40ms.