support for scalar args to aten::scatter

[linshokaku]

close #2600

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.96%. Comparing base (6718ef0) to head (eeaa9d8).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2613   +/-   ##
=======================================
  Coverage   69.95%   69.96%           
=======================================
  Files         222      222           
  Lines       26311    26317    +6     
  Branches     2604     2607    +3     
=======================================
+ Hits        18406    18412    +6     
  Misses       6993     6993           
  Partials      912      912           

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