Feature: prefetch ranged requests

[jim3ma]

Description

When download ranged requests, eg: http://example.com/file with header "Range: bytes=0-63", we can prefetch the whole file with http://example.com/file. After done these, other requests, eg: http://example.com/file with header "Range: bytes=64-127", can speed up.

1. Add prefetch option in dfget.yaml.
2. Support reuse parent when download ranged requests.

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:

• Code compiles correctly.
• My code follows the code style of this project.
• 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.
• All new and existing tests passed.

[codecov-commenter]

Codecov Report

Merging #1053 (ff532e4) into main (a855c0e) will decrease coverage by 0.48%.
The diff coverage is 23.83%.

@@            Coverage Diff             @@
##             main    #1053      +/-   ##
==========================================
- Coverage   46.24%   45.75%   -0.49%     
==========================================
  Files         129      129              
  Lines        9390     9534     +144     
==========================================
+ Hits         4342     4362      +20     
- Misses       4564     4679     +115     
- Partials      484      493       +9     

Flag	Coverage Δ
Object-compatibility-e2etests	?
e2etests	?
unittests	45.75% <23.83%> (-0.49%)	⬇️

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

Impacted Files	Coverage Δ
client/clientutil/range.go	87.03% <0.00%> (-1.65%)	⬇️
client/config/peerhost.go	35.29% <ø> (ø)
client/daemon/daemon.go	5.41% <0.00%> (ø)
client/daemon/peer/peertask_file.go	56.69% <0.00%> (-0.91%)	⬇️
client/daemon/peer/peertask_manager.go	33.65% <0.00%> (-10.65%)	⬇️
client/daemon/storage/local_storage.go	22.54% <0.00%> (-0.86%)	⬇️
client/daemon/storage/storage_manager.go	19.20% <ø> (ø)
client/dfget/dfget.go	13.40% <0.00%> (-0.23%)	⬇️
client/daemon/transport/transport.go	51.38% <20.68%> (-6.60%)	⬇️
client/daemon/peer/peertask_reuse.go	52.02% <30.58%> (-29.23%)	⬇️
... and 8 more