Adding an option to add HTTP request duration information

**Is your feature request related to a problem? Please describe.**
We have the need of getting the HTTP request duration of the remote calls that have been involved within HTTP calls that uses this SDK.

The library already provides an option to enable the debug logging where we can get the full HTTP request and response: https://github.com/googleapis/google-http-java-client/blob/4e3b3c3cebeb8439e729a9f99b58e5fc5e13e2cf/google-http-client/src/main/java/com/google/api/client/http/HttpRequest.java#L890

However there is no information about how long the request happened.
Do you have any plan to add the option to add this information when the debug logs is enabled ?

**Describe the solution you'd like**
An option to show HTTP request duration while enabling debug logging mode.

**Describe alternatives you've considered**
We added another listener to calculate the request duration and print it as a separate logs, which makes it harder to correlate the request duration with the rest of other information while debugging if a lot of HTTP requests are executed in parallel.

**Additional context**
N/A