Allow Int in Reshape

[AntonOresten]

• Allow a contiguous sequence of integers or colons (sizes::Union{Int, Colon}...) in a reshape operation, getting replaced by Split(.., sizes).
• Allow up to 4 leading non-LocalReshape arguments in Base.reshape (up from one colon or ellipsis).
• Add Split(sizes...) method.

[codecov]

Codecov Report

❌ Patch coverage is 62.92135% with 33 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.19%. Comparing base (2de2dcb) to head (25b73a5).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/Reshape/Reshape.jl	57.50%	17 Missing ⚠️
src/Reshape/utils.jl	76.92%	9 Missing ⚠️
src/enhanced-base/reshape.jl	14.28%	6 Missing ⚠️
src/Reshape/LocalReshape.jl	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #13      +/-   ##
==========================================
- Coverage   81.59%   79.19%   -2.40%     
==========================================
  Files          14       14              
  Lines         652      721      +69     
==========================================
+ Hits          532      571      +39     
- Misses        120      150      +30     

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