fix(restapi): Add cors headers when the request is returning errors

[2-towns]

Currently, the REST endpoints don't return the CORS headers when they return an error.

One of the reasons is that Nim Presto has a weird behavior of adding the Access-Control-Allow-Origin header when a request is successful and omitting it when the request returns an error (see the method processRestRequest in nim-presto/presto/serverprivate.nim).

This PR fixes this behavior by adding the CORS headers whenever a response is returned. I was hesitant to create an OPTIONS endpoint for every request, as we did for the data upload, but it does not work with simple requests because no OPTIONS request is sent by the browser in that case.

Without the CORS headers returned when an endpoint returns an error, I am unable to display the error message to the user. Moreover, I am not able to know if the Marketplace is enabled or not (see codex-storage/codex-marketplace-ui#29).

[AuHau]

Yeah it is pain that Presto does not handle this 😳 But yeah otherwise LGTM. Just fix the tests ;-)

[2-towns]

Just fix the tests ;-)

I just ran the testAll and I have three tests failing:

[Suite] Marketplace contracts
  [FAILED] can be paid out at the end, specifying reward and collateral recipient

[Suite] On-Chain Market
  [FAILED] supports slot reservations full subscriptions
  [FAILED] pays rewards to reward recipient, collateral to host

But it doesn't seem related to my commit. Do you have specific tests that I should look into? @AuHau

[2-towns]

Just fix the tests ;-)

I just ran the testAll and I have three tests failing:

[Suite] Marketplace contracts
  [FAILED] can be paid out at the end, specifying reward and collateral recipient

[Suite] On-Chain Market
  [FAILED] supports slot reservations full subscriptions
  [FAILED] pays rewards to reward recipient, collateral to host

But it doesn't seem related to my commit. Do you have specific tests that I should look into? @AuHau

I just reran the tests and it worked