S3UTILS-226 MPU orphan cleanup script

[jonathan-gramain]

Implement cleanupMpuOrphans.js to delete orphaned parts and sproxyd keys.

Orphaned parts are part metadata which do not correspond to an overview key with the same upload ID.

Sproxyd keys are only removed if no completed MPU object has a matching upload ID in the same bucket.

[codecov]

Codecov Report

❌ Patch coverage is 61.67401% with 87 lines in your changes missing coverage. Please review.
✅ Project coverage is 44.87%. Comparing base (da19184) to head (3386bfa).

Files with missing lines	Patch %	Lines
cleanupMpuOrphans.js	61.67%	86 Missing and 1 partial ⚠️

Additional details and impacted files

@@                                       Coverage Diff                                       @@
##           improvement/S3UTILS-225-list-bucketd-versions-full-metadata     #380      +/-   ##
===============================================================================================
+ Coverage                                                        44.21%   44.87%   +0.65%     
===============================================================================================
  Files                                                               84       85       +1     
  Lines                                                             5819     6046     +227     
  Branches                                                          1237     1282      +45     
===============================================================================================
+ Hits                                                              2573     2713     +140     
- Misses                                                            3201     3287      +86     
- Partials                                                            45       46       +1     

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