Proxy requests via GSB

[staszek-krotki]

yagna needs a http endpoint to proxy http requests via GSB

• add an endpoint /activity/{id}/_http_request/{postfix_path}
  {postfix_path} will be used to add to the base-url of the framework on provider's side
• runtime translates the address: takes the local base-address of framework and adds postfix_path (with query params)
• endpoint listens to GET/POST/PATCH/PUT/DELETE
• headers supported: proxy all headers except yagna-specific, cors, ...possibly more, security research needed
• body is proxied as is

runtime listens to GSB and responds in the same way

• support all types of responses: events. streams etc.