Persist TaskRun logs with timestamps (opt-in)

[thomascube]

Feature request

I'd like to have timestamp information in the logs persisted by Tekton Results.
Basically the equivalent of kubectl logs --timestamps

Of course this should be opt-in and configurable by a config option.

Use case

For long running pipeline tasks, exact timing information for each log line can be helpful to determine where the elapsed time was spent. We have a custom UI built for Tekton which can show/hide timestamps in logs. Instead of pulling the logs ourselves, we'd like to use Tekton results' logging feature to persist logs and consume them via the API.

[manuelwallrapp]

We also need this feature. Eventually we can figure out how to adapt it and do a PR.