Provide a way to customize time unit for `Logging{Service,Client}`

[ikhoon]

A nanosecond and microsecondare used a default time unit for LoggingService and LoggingClient.

INFO c.l.a.s.l.LoggingService - [sreqId=...][h1c://foo.com/foo#GET] Request: ... duration=45446µs(45446187ns), scheme=none+h1c, user-agent=Mozilla/5.0...]}
INFO c.l.a.s.l.LoggingService - [sreqId=...][h1c://foo.com/foo#GET] Response: ... duration=16875µs(16875233ns), totalDuration=54124µs(54124177ns), headers=[...]}

Some users may want to use a millisecond or second unit for readabiliy. For example:

LoggingService.builder()
              .timeUnit(TimeUnit.MILLISECONDS)
              // or
              .timeUnit(TimeUnit.SECODNS, /* precision */ 6)
              ...
              .build()

INFO c.l.a.s.l.LoggingService - [sreqId=...][h1c://foo.com/foo#GET] Request: ... duration=45.446ms(45446187ns), scheme=none+h1c, user-agent=Mozilla/5.0...]}
INFO c.l.a.s.l.LoggingService - [sreqId=...][h1c://foo.com/foo#GET] Response: ... duration=16.875ms(16875233ns), totalDuration=54124µs(54124177ns), headers=[...]}

[trustin]

We may want to introduce a generic text formatter interface that replaces the static TextFormatter.

[tomatophobia]

Hi @ikhoon, if this issue is still ongoing, may I handle it?

[ikhoon]

4267 adds a new interface to customize the log format. I'm happy with your interest. However, I recommend you start this issue after #4267 is merged to minimize conflicts.

[tomatophobia]

Thanks for checking 👍 That might resolve this issue as well. I will try it after #4267 is merged, if the issue is still present. Thanks again!