Add option to clear metadata in ort fusion

[gramalingam]

Add option to clear metadata in ort fusion. Otherwise, we lose all metadata after running ORT fusion

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.14%. Comparing base (971f9bb) to head (8d6a4e5).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
onnxscript/rewriter/ort_fusions/_core.py	0.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2685      +/-   ##
==========================================
- Coverage   70.15%   70.14%   -0.01%     
==========================================
  Files         225      225              
  Lines       27039    27044       +5     
  Branches     2716     2718       +2     
==========================================
+ Hits        18968    18969       +1     
- Misses       7134     7136       +2     
- Partials      937      939       +2     

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