Fix transaction ID implementation and verify Event.body is indeed base64 when isBase64 is true.

[selectiveduplicate]

Will bump the version when we approve of the chanegs. 🙂

Screenshots from a working example with Serverless and the current patch

See screenshot

See screenshot

Output from the added local tests

;; node --test
▶ testing response for async/await Lambda
  ✔ should contain 'X-Moesif-Transaction-Id' header (0.960301ms)
  ✔ should have 'application/json' as the 'Content-Type' header (0.501034ms)
  ✔ should have expected body (0.20235ms)
  ✔ should have '200 OK' status code (0.203222ms)
▶ testing response for async/await Lambda (3.188207ms)
{
  userId: 1,
  id: 1,
  title: 'sunt aut facere repellat provident occaecati excepturi optio reprehenderit',
  body: 'quia et suscipit\n' +
    'suscipit recusandae consequuntur expedita et cum\n' +
    'reprehenderit molestiae ut ut quas totam\n' +
    'nostrum rerum est autem sunt rem eveniet architecto'
}
▶ testing response for callback-style Lambda
  ✔ should contain 'X-Moesif-Transaction-Id' header (0.957489ms)
  ✔ should have 'application/json' as the 'Content-Type' header (0.483045ms)
  ✔ should have expected body (0.191357ms)
  ✔ should have '200 OK' status code (0.171779ms)
▶ testing response for callback-style Lambda (3.15757ms)
{
  userId: 1,
  id: 1,
  title: 'sunt aut facere repellat provident occaecati excepturi optio reprehenderit',
  body: 'quia et suscipit\n' +
    'suscipit recusandae consequuntur expedita et cum\n' +
    'reprehenderit molestiae ut ut quas totam\n' +
    'nostrum rerum est autem sunt rem eveniet architecto'
}
ℹ tests 8
ℹ suites 2
ℹ pass 8
ℹ fail 0
ℹ cancelled 0
ℹ skipped 0
ℹ todo 0
ℹ duration_ms 1057.238274