DoD

• pmm-admin summary --pprof should fetch pprof profiles and add them to the summary file.

Implementation

• Add boolean --pprof flag to summary command.
• Fetch profiles from pmm-agent (port 7777) and, if --skip-server is not passed, from pmm-managed (port 7773) and qan-api2 (port 9933).
• Fetch profiles from different processes simultaneously to reduce total time. Do not fetch several profiles from the same process at the same time.
• Log progress at it takes to fetch some profiles.
• URLs to fetch (with proper ports) in that order:
  • http://127.0.0.1:7777/debug/pprof/profile?seconds=60 (profile.pb.gz)
  • http://127.0.0.1:7777/debug/pprof/heap?gc=1 (heap.pb.gz)
  • http://127.0.0.1:7777/debug/pprof/trace?seconds=10 (trace.out)
• Add those files to summary archive without unpacking.

DOC: In troubleshooting section of our documentation we need to explain how to use this flag to collect additional files