Request Authorizer on API Gateway V2 fails before lambda is triggered

## Bug Report

Lambda based authorizers for API Gateway should not fail before the lambda itself gets called.

**Current Behavior**

If there is no identity source (either token or query string), the `AuthScheme` will automatically return an `unauthorized` result, leading to the API request to fail.

**Expected behavior/code**

The event passed into the Authorizer should have undefined `authorizationToken` and `identitySource` fields, but it should be up to the Authorizer Lambda to pass/fail the request. This would be in line with AWS's behaviour.

**Environment**

- `serverless` version: 3.30.1
- `serverless-offline` version: 12.0.4
- `node.js` version: 18.14
- `OS`: Windows 10

**Possible Solution**

Remove the automatic fail [at these lines](https://github.com/dherault/serverless-offline/blob/5b198a752c8cfdcbde5e3eb7e041a64ac3626289/src/events/http/createAuthScheme.js#L84-L86).