support hostpath for mount pod

[zwwhdls]

complete #592

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.44% 🎉

Comparison is base (bef5de7) 38.64% compared to head (8716de7) 39.09%.
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #703      +/-   ##
==========================================
+ Coverage   38.64%   39.09%   +0.44%     
==========================================
  Files          33       33              
  Lines        3959     3988      +29     
==========================================
+ Hits         1530     1559      +29     
  Misses       2283     2283              
  Partials      146      146              

Files Changed	Coverage Δ
pkg/config/config.go	0.00% <ø> (ø)
pkg/config/setting.go	75.00% <100.00%> (+0.67%)	⬆️
pkg/juicefs/mount/builder/pod.go	52.94% <100.00%> (+6.59%)	⬆️

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