Support for lecun normal weight initialization

[RohitRathore1]

feat: Add LeCun normal weight initialization

• Implemented lecun_normal function for weight initialization based on fan-in.
• Provided default initializer for flexibility.
• Marked lecun_normal as non-differentiable using ChainRulesCore.

It resolves issue #2290

[Edit: closes #2290, closes #2491, closes #2299]

PR Checklist

• Tests are added
• Entry in NEWS.md
• Documentation, if applicable

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.

Project coverage is 77.42%. Comparing base (1348828) to head (56f36c2).
Report is 160 commits behind head on master.

Files with missing lines	Patch %	Lines
src/utils.jl	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2311      +/-   ##
==========================================
- Coverage   79.47%   77.42%   -2.05%     
==========================================
  Files          31       31              
  Lines        1749     1750       +1     
==========================================
- Hits         1390     1355      -35     
- Misses        359      395      +36     

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