feat: support proxy for the generic download

[LinuxSuRen]

No description provided.

[codecov]

Codecov Report

Merging #316 (5da406c) into master (5162176) will decrease coverage by 0.96%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master     #316      +/-   ##
==========================================
- Coverage   43.86%   42.91%   -0.96%     
==========================================
  Files          29       30       +1     
  Lines        2020     2109      +89     
==========================================
+ Hits          886      905      +19     
- Misses       1092     1161      +69     
- Partials       42       43       +1     

Flag	Coverage Δ
unittests	42.91% <33.33%> (-0.96%)	⬇️

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Impacted Files	Coverage Δ
cmd/install.go	33.33% <0.00%> (-0.98%)	⬇️
pkg/os/generic_installer.go	8.73% <0.00%> (-1.85%)	⬇️
pkg/os/installer.go	80.95% <50.00%> (-3.54%)	⬇️
pkg/os/generic/common.go	30.90% <70.83%> (ø)

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