See https://github.com/RevenueCat/khepri/pull/6798.
This can help debug issues as it helps us cross-reference requests on
our end.
### Changes:
- Logging `X-Request-ID` and `X-Amzn-Trace-ID` headers if present (only
in verbose mode)
- Logging these even for failed requests
- Also logging `request_handled_by_load_shedder` for failed requests
- To accomplish that. `HTTPURLResponse` now conforms to our
`HTTPResponseType`, this allows us to extract headers in an uniform way
### Example:
```
[network] DEBUG: ℹ️ API request completed: GET '/v1/subscribers/$RCAnonymousID%3Ad9dc4f3b33054cf28c0f2ec9da0f48d5' (304)
Request-ID: 'be534c50-5231-403b-be2f-7c077861751d'; Amzn-Trace-ID: 'Root=1-6532c6ca-7ef80f961ec9c4145484df13'
```
We were currently logging the status code retrieved from `ETagManager`,
which made it seem like etags weren't working.
Example:
> API request completed: GET /v1/subscribers/identify (200)
With this change, we now log the actual response status code so we can
verify the server is returning the correct status code:
> API request completed: GET /v1/subscribers/identify (304)
Rick