Thread-level monitoring (similar to top -H)

## Feature Request

Telegraf procstat plugin helps to monitor various processes on the system, but does not take into account the multi-threaded processes (all running with the same main pid , but different thread ids)
In Linux, the "top -H" command gives a thread-level metric output.

### Proposal:
Add a plugin or extension to procstat/processor plugin to enable thread-level monitoring

### Current behavior:
Process-level aggregated output is displayed/stored

### Desired behavior:
Thread-level output is desired

### Use case: [Why is this important (helps with prioritizing requests)]
Many processes are multi-threaded and run on different cpus (or vcpus) , and the process output would be an aggregate of all .