refactor(middleware): remove aws-lambda handler

[baoshan]

This PR fixes #332. Something to be mentioned:

1. I removed the onUnhandledRequest option. Callers can still custom unhandled requests: use the express * router (as covered by the test cases) or check if the response is a 404.
2. I removed fromentries because we’re not supporting Node.js v10/12.
3. I refactored the tests. node-middleware.test.ts and web-worker-handler.test.ts are small now because the source files are small.

I am not sure if someone relies on the aws-lambda middleware. I would like to help (just open an issue).

[baoshan]

I tried really hard to bypass the “Hard-coded credentials” only found she is smarter than me.

[wolfy1339]

I tried really hard to bypass the “Hard-coded credentials” only found she is smarter than me.

Those can be safely ignored. They are known false positives since in this case they are not valid access tokens and only used in documentation

[wolfy1339]

Let's split out the changes into a different PR, and focus on removing aws-lamba in this one

[baoshan]

Great suggestion. This PR only removes the lambda handler.