WIP : Introduce CORS and make ways to add authentication

Fixes #921

Code design subject to change for a bit more time. This is because I am parallely looking at WorkerGateway Authentication design doc to see where does that fit in.

Also please read: https://www.notion.so/golemcloud/CORS-in-Worker-Gateway-Draft-105a4cb355ec80c58253c80b483a08af?pvs=25#136a4cb355ec80eb8116d26521bb5a3b

Restructure - so that we have clear introduction of new plugins and authentication modules. Find the image below. The prefix gateway is helping as a developer, however will disappear once we can move this out of worker-service-base to gateway module. worker-service can of course reuse this module (i.e, not introducing another network traffic between gateway and worker). I understand restructuring could make the PR review harder, but I will make more comments within PR to make the review easy later on.
Introduce proper plugins (Kong inspired). [After comments from @jdegoes in NOTION docs, , I am changing the name to middleware)
Plugins can be part of a binding (example: worker binding), or plugin by itself can be a binding. Both are needed. Example certain pre-flight requests just need to know only a plugin and shouldn't know anything else on the backend. This is well typed now. Tomorrow FileServer (IFS PR) can be part of the same enum. Probably we should rename types with prefix or suffix as binding to integration. AWS call it integration.
Support both concise and verbose versions of CORS - OpenAPI spec supports both and native Api Definition supports only concise. This is the best I could come up with.
Ensuring backward compatibility ensured both from REST API perspective and GRPC proto. This was a bit of work
OpenAPI spec fix to support binding at Operator level
CORS workflow has already been tried out and made it work, however, I made more changes in design afterwards. Setting up CORS was the easiest part of the PR

golemcloud / golem

WIP : Introduce CORS and make ways to add authentication #1053