Perf protocol

[lchenut]

First draft of the perf protocol.

A few tests are necessary, but overall I think it's correct.

[codecov]

Codecov Report

Merging #925 (7148f29) into unstable (56c23a2) will decrease coverage by 0.04%.
Report is 1 commits behind head on unstable.
The diff coverage is 100.00%.

Additional details and impacted files

@@             Coverage Diff              @@
##           unstable     #925      +/-   ##
============================================
- Coverage     83.51%   83.47%   -0.04%     
============================================
  Files            91       91              
  Lines         15145    15145              
============================================
- Hits          12649    12643       -6     
- Misses         2496     2502       +6     

Files Changed	Coverage Δ
libp2p/transports/wstransport.nim	85.98% <100.00%> (ø)

... and 3 files with indirect coverage changes

[mxinden]

🚀 thanks for working on this!

[diegomrsantos]

@lchenut maybe we can slipt it in client and server files?

[mxinden]

🚀 let me know in case you need any help integrating this into https://github.com/libp2p/test-plans/tree/master/perf.