refactor: support hdfs for backend

[gaius-qi]

Description

Related Issue

Motivation and Context

Screenshots (if appropriate)

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 9 lines in your changes missing coverage. Please review.

Project coverage is 32.60%. Comparing base (8ce9f23) to head (934cfa6).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
dragonfly-client/src/bin/dfget/main.rs	0.00%	7 Missing ⚠️
dragonfly-client-backend/src/http.rs	90.00%	1 Missing ⚠️
dragonfly-client-backend/src/lib.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #852      +/-   ##
==========================================
- Coverage   32.62%   32.60%   -0.02%     
==========================================
  Files          57       57              
  Lines        8686     8682       -4     
==========================================
- Hits         2834     2831       -3     
+ Misses       5852     5851       -1     

Files with missing lines	Coverage Δ
dragonfly-client-backend/src/hdfs.rs	13.86% <ø> (-1.85%)	⬇️
dragonfly-client-backend/src/http.rs	96.94% <90.00%> (ø)
dragonfly-client-backend/src/lib.rs	97.58% <0.00%> (-0.80%)	⬇️
dragonfly-client/src/bin/dfget/main.rs	26.38% <0.00%> (+0.06%)	⬆️

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[chlins]

lgtm

[BruceAko]

LGTM