feat: pex support parent task

[jim3ma]

Description

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]

Codecov Report

Attention: Patch coverage is 4.87805% with 39 lines in your changes are missing coverage. Please review.

Project coverage is 52.62%. Comparing base (3ddf37a) to head (ba71ec4).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3274      +/-   ##
==========================================
- Coverage   52.68%   52.62%   -0.06%     
==========================================
  Files         192      192              
  Lines       20397    20422      +25     
==========================================
+ Hits        10747    10748       +1     
- Misses       8843     8869      +26     
+ Partials      807      805       -2     

Flag	Coverage Δ
unittests	52.62% <4.87%> (-0.06%)	⬇️

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

Files	Coverage Δ
client/daemon/peer/peertask_stream.go	61.13% <0.00%> (-0.88%)	⬇️
client/daemon/transport/transport.go	35.46% <5.40%> (-2.48%)	⬇️

... and 2 files with indirect coverage changes