Update Eigen to the latest

[snnn]

Changes related to Eigen:

1. Update eigen.cmake: Removed the use of cmake's fetchcontent_populate command as it is deprecated.
2. Upgrade Eigen: Updated Eigen to the latest version to resolve a build issue. Without this update, the Android build would check for a Fortran compiler and report an error when running cmake config in Eigen's source directory.
3. Add Eigen as a vcpkg port: Added Eigen as a vcpkg port since the official vcpkg repository version is outdated.
4. Remove eigen_INCLUDE_DIRS variable: Removed the eigen_INCLUDE_DIRS cmake variable and replaced it with Eigen3::Eigen.

This change enables building ONNX Runtime(CPU EP only) as a vcpkg port. To do so, you also need to download the
ports/onnxruntime/vcpkg.json file from this PR: microsoft/vcpkg#36850

[github-actions]

You can commit the suggested changes from lintrunner.

[snnn]

@ranjitshs , could you please help me update the patch file(cmake/patches/eigen/eigen-aix.patch) for AIX?

[ranjitshs]

@ranjitshs , could you please help me update the patch file(cmake/patches/eigen/eigen-aix.patch) for AIX?

Sure. I will use this branch snnn/vcpkg_eigen and update the AIX patch , combining the exiting patch with the one provided in this.
Will raise PR once this is merged.