Implement corrcoef function in keras.ops

[shashaka]

Adds keras.ops.corrcoef, which computes the Pearson correlation coefficient matrix. Supported across NumPy, TensorFlow, PyTorch, and JAX backends, but not supported on OpenVINO.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 85.93750% with 9 lines in your changes missing coverage. Please review.

Project coverage is 82.67%. Comparing base (81821e0) to head (425d676).
Report is 26 commits behind head on master.

Files with missing lines	Patch %	Lines
keras/src/backend/tensorflow/numpy.py	76.19%	3 Missing and 2 partials ⚠️
keras/src/ops/numpy.py	88.23%	1 Missing and 1 partial ⚠️
keras/api/_tf_keras/keras/ops/__init__.py	0.00%	1 Missing ⚠️
keras/api/_tf_keras/keras/ops/numpy/__init__.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #21372      +/-   ##
==========================================
+ Coverage   82.65%   82.67%   +0.01%     
==========================================
  Files         565      565              
  Lines       54802    55057     +255     
  Branches     8508     8567      +59     
==========================================
+ Hits        45297    45518     +221     
- Misses       7413     7441      +28     
- Partials     2092     2098       +6     

Flag	Coverage Δ
keras	82.48% <85.93%> (+0.01%)	⬆️
keras-jax	63.50% <34.37%> (-0.08%)	⬇️
keras-numpy	58.67% <43.75%> (-0.08%)	⬇️
keras-openvino	33.44% <29.68%> (+0.30%)	⬆️
keras-tensorflow	63.90% <54.68%> (-0.10%)	⬇️
keras-torch	63.53% <40.62%> (-0.12%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[fchollet]

Nice work, thank you for the PR!

[fchollet]

LGTM, thank you!