Various Fixups for klone download

[mtauraso]

• Added configs so image/variance/mask layer downloads can be configured.
• Put filter lower in the sort order for dC.Rect so that duplicate dowloading in a resume situation is minimized for large downloads.
• Concurrent connection error is now correct to our understanding of HSC's server-side behavior.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 38.90%. Comparing base (3ee8380) to head (2ba53fd).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/fibad/download.py	0.00%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #62   +/-   ##
=======================================
  Coverage   38.90%   38.90%           
=======================================
  Files          17       17           
  Lines         712      712           
=======================================
  Hits          277      277           
  Misses        435      435           

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[github-actions]

Before [3ee8380]	After [55ecdc1]	Ratio	Benchmark (Parameter)
2.44±1s	3.40±1s	~1.39	benchmarks.time_computation
1.38k	1.83k	1.32	benchmarks.mem_list

Click here to view all benchmarks.

[aritraghsh09]

This looks good.
While reading the code, an enhancement came to mind which won't be needed for our work, but might be important later for other users.
I have opened the issue here -- #63