feat(event-handler): implement mechanism to manipulate response in middleware

[svozza]

Summary

This commit introduces a mechanism for middleware to manipulate HTTP responses sent by the handler. This is required for middleware such as CORS.

Changes

BaseRouter.ts

• HandlerOptions now exposes a res field. This is a Web API Response object that represents the response that will be sent. This allows middleware that runs after the handler has been executed to manipulate the response before it is finally sent
• The middleware that runs the handler now does not return the result but mutates the res field and adds the response there
• Renamed RequestOptions to RequestContext because it now deals with responses as well as requests

Converters.ts

• Created new function to convert HandlerResponse for a Web API Response object.

Tests:

• Added middleware header precedence testing ('last write wins' behavior)
• Added tests for new handlerResultToResponse fucntion
• Implemented direct unit tests for composeMiddleware

Issue number: closes #4393

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
17.5% Duplication on New Code

See analysis details on SonarQube Cloud