Use separate activity to report Chunk dl reading progress.

[Al12rs]

Fixes download getting double the progress value
Fixes #834

[codecov-commenter]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (2f65741) 60.25% compared to head (b1588fd) 60.30%.
Report is 1 commits behind head on main.

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #835      +/-   ##
==========================================
+ Coverage   60.25%   60.30%   +0.05%     
==========================================
  Files         594      594              
  Lines       18130    18104      -26     
  Branches     1372     1382      +10     
==========================================
- Hits        10924    10918       -6     
+ Misses       6885     6869      -16     
+ Partials      321      317       -4     

Flag	Coverage Δ
Linux	59.66% <83.33%> (+0.06%)	⬆️
Windows	59.52% <83.33%> (+0.07%)	⬆️
clean_environment_tests	60.29% <83.33%> (+0.05%)	⬆️
network_tests	?

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

Files	Coverage Δ
...etworking.HttpDownloader/AdvancedHttpDownloader.cs	78.23% <100.00%> (+0.20%)	⬆️
...ds.Networking.Downloaders/Tasks/NxmDownloadTask.cs	0.00% <0.00%> (ø)

... and 41 files with indirect coverage changes

[Sewer56]

This is probably good.
Just in case, CC @halgari