always use tmp dir to load model

[lxning]

Description

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Please include a summary of the feature or issue being fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

Fixes #(issue)
#2454

Type of change

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• Bug fix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

Feature/Issue validation/testing

This is workaround solution to fix 3rd party dependency installation on SM. It always uses tmp dir to load model and install 3rd party dependency. If the model url is a dir, it creates a symbolic link under tmp to link with the url.

Please describe the Unit or Integration tests that you ran to verify your changes and relevant result summary. Provide instructions so it can be reproduced.
Please also list any relevant details for your test configuration.

• Test
  all existing ci/regression tests should be pass

Checklist:

• Did you have fun?
• Have you added tests that prove your fix is effective or that this feature works?
• Has code been commented, particularly in hard-to-understand areas?
• Have you made corresponding changes to the documentation?

[codecov]

Codecov Report

Merging #2535 (6691401) into master (921f423) will decrease coverage by 0.21%.
Report is 11 commits behind head on master.
The diff coverage is 58.69%.

❗ Current head 6691401 differs from pull request most recent head 4ee03ef. Consider uploading reports for the commit 4ee03ef to get more accurate results

@@            Coverage Diff             @@
##           master    #2535      +/-   ##
==========================================
- Coverage   72.85%   72.64%   -0.21%     
==========================================
  Files          78       79       +1     
  Lines        3695     3733      +38     
  Branches       58       58              
==========================================
+ Hits         2692     2712      +20     
- Misses        999     1017      +18     
  Partials        4        4              

Files Changed	Coverage Δ
ts/context.py	67.53% <ø> (ø)
ts/metrics/metric_cache_yaml_impl.py	93.24% <ø> (ø)
ts/handler_utils/timer.py	32.00% <32.00%> (ø)
...orch_handler/unit_tests/test_utils/mock_context.py	86.95% <66.66%> (-3.05%)	⬇️
ts/torch_handler/request_envelope/kservev2.py	90.27% <85.71%> (+0.27%)	⬆️
ts/torch_handler/base_handler.py	69.09% <100.00%> (+0.57%)	⬆️
ts/torch_handler/image_classifier.py	90.00% <100.00%> (+1.11%)	⬆️
ts/torch_handler/vision_handler.py	90.90% <100.00%> (+0.58%)	⬆️

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