Add SpacingLayout support

[Kyle-Ye]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 30.99%. Comparing base (78e8a28) to head (c98f9e7).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
Sources/OpenSwiftUICore/Layout/SpacingLayout.swift	0.00%	12 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #602      +/-   ##
==========================================
- Coverage   30.99%   30.99%   -0.01%     
==========================================
  Files         530      531       +1     
  Lines       31782    31794      +12     
==========================================
+ Hits         9851     9853       +2     
- Misses      21931    21941      +10     

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