Uncontrolled input fix for ModelManager

[msaroufim]

Fixes
https://github.com/pytorch/serve/security/code-scanning/36
https://github.com/pytorch/serve/security/code-scanning/34

[codecov]

Codecov Report

Merging #2635 (8ac8305) into master (d8a1146) will not change coverage.
Report is 3 commits behind head on master.
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##           master    #2635   +/-   ##
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  Files          85       85           
  Lines        3905     3905           
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  Misses       1115     1115           
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[lxning]

We only need replace string with string[] for Runtime exec.

[lxning]

This might break some cx environment setting such as SageMaker, where model dir is readonly.