Include parent directory validation check for deepspeed

[ishandutta0098]

What does this PR do?

Included a check for the checkpoint parent directory and enhanced the error message making the checkpoint validation more robust

• Added a check to see if the passed checkpoint directory is a valid deepspeed directory
• Raised an error indicating the checkpoint directory to be passed should be the parent directory

Fixes #17763

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[codecov]

Codecov Report

Merging #17795 (467f064) into master (080eaf3) will decrease coverage by 25%.
The diff coverage is 14%.

❗ Current head 467f064 differs from pull request most recent head 5d41cbf. Consider uploading reports for the commit 5d41cbf to get more accurate results

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #17795     +/-   ##
=========================================
- Coverage      84%      59%    -25%     
=========================================
  Files         430      420     -10     
  Lines       32667    31977    -690     
=========================================
- Hits        27319    18862   -8457     
- Misses       5348    13115   +7767     

[carmocca]

Nice improvement in usability