feat: add traffic shaper for download tasks

[greenhandatsjtu]

Signed-off-by: greenhandatsjtu sunhengke@sjtu.edu.cn

Description

For now, when a peer download from seed peers, the speed is limited by perPeerRateLimit and totalRateLimit.
However, when there's only one task running with perPeerRateLimit set to 20M and totalRateLimit set to 100M, then 80% of the bandwidth is wasted. That's why we introduce traffic shaper.
With the help of sampling traffic shaper, the rate limit of every task can be dynamically adjusted based on the context, the download speed of all tasks in the past second, which significantly improves the download performance.

Related Issue

Motivation and Context

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation Update (if none of the other choices apply)

Checklist

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.

[codecov-commenter]

Codecov Report

Merging #1654 (2fef1de) into main (5d5ea63) will increase coverage by 0.19%.
The diff coverage is 84.37%.

@@            Coverage Diff             @@
##             main    #1654      +/-   ##
==========================================
+ Coverage   42.03%   42.22%   +0.19%     
==========================================
  Files         125      126       +1     
  Lines       15436    15594     +158     
==========================================
+ Hits         6488     6585      +97     
- Misses       8432     8491      +59     
- Partials      516      518       +2     

Flag	Coverage Δ
Object-compatibility-e2etests	?
e2etests	?
unittests	42.22% <84.37%> (+0.19%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
client/config/peerhost.go	35.73% <ø> (ø)
client/daemon/peer/peertask_manager.go	26.08% <50.00%> (+0.41%)	⬆️
client/daemon/peer/traffic_shaper.go	86.01% <86.01%> (ø)
client/daemon/peer/peertask_conductor.go	57.61% <100.00%> (-0.23%)	⬇️
client/daemon/peer/peertask_piecetask_poller.go	32.78% <0.00%> (-14.21%)	⬇️
client/daemon/rpcserver/subscriber.go	48.85% <0.00%> (-1.73%)	⬇️
client/daemon/peer/piece_manager.go	52.83% <0.00%> (-0.14%)	⬇️

[gaius-qi]

LGTM