Fix the dataset merge, export on Machine B

[JSabadin]

Purpose

Bug description:
When a dataset created on GCS is pulled down to Machine B and used as a local dataset, attempting to merge it with another local dataset on Machine B produces an invalid dataset. Notably, merging two datasets directly on the cloud from different machines worked correctly prior to this.

This edge case has been addressed in this PR, and a corresponding test has been added.

Additionally, the export now includes metadata such as text for OCR.

Specification

None / not applicable

Dependencies & Potential Impact

None / not applicable

Deployment Plan

None / not applicable

Testing & Validation

None / not applicable

[codecov]

Codecov Report

Attention: Patch coverage is 94.59459% with 2 lines in your changes missing coverage. Please review.

Project coverage is 95.57%. Comparing base (f2cf992) to head (c7d8f73).
Report is 2 commits behind head on main.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
luxonis_ml/data/datasets/luxonis_dataset.py	87.50%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #327      +/-   ##
==========================================
+ Coverage   95.55%   95.57%   +0.02%     
==========================================
  Files         102      102              
  Lines        6071     6104      +33     
==========================================
+ Hits         5801     5834      +33     
  Misses        270      270              

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