[Core] Rename BaseObject to BaseComponent

[alxbilger]

This PR implements a backward-compatible transition of the core object base type from BaseObject to BaseComponent while ensuring existing code continues to compile during migration:

• Renamed core types: All forward declarations, casts, and visitor APIs operating on objects now use BaseComponent (the new type).
• Backward compatibility layer:
  • BaseObject is a deprecated alias for BaseComponent (ensures existing code compiles without changes).
  • #include <BaseObject.h> is a deprecated alias for #include <BaseComponent.h> (via header shim).
  • toBaseObject() is a deprecated alias for toBaseComponent() (forwarded internally to avoid breaking core builds).
• Build configuration: Compatibility headers are exposed to downstream consumers via include directories.
• ⚠️ Critical migration note:

This deprecation layer does not work for code using its own forward-declared BaseObject. Such code will fail with a redefinition error (e.g., BaseObject already defined). Instead of the forward declaration of BaseObject, we recommand to include <sofa/core/fwd.h>. Then, you can rename BaseObject with BaseComponent, although the deprecation layer should work.

[ci-depends-on https://github.com/sofa-framework/SofaPython3/pull/575]
[ci-depends-on https://github.com/sofa-framework/Sofa.Qt/pull/30]

[ci-build][with-all-tests]

---

By submitting this pull request, I acknowledge that
I have read, understand, and agree SOFA Developer Certificate of Origin (DCO).

---

Reviewers will merge this pull-request only if

• it builds with SUCCESS for all platforms on the CI.
• it does not generate new warnings.
• it does not generate new unit test failures.
• it does not generate new scene test failures.
• it does not break API compatibility.
• it is more than 1 week old (or has fast-merge label).

[fredroy]

[ci-build][with-all-tests]

[sofabot]

[ci-depends-on] detected during build #5.

All dependencies are merged/closed. Congrats! 👍

[sofabot]

[ci-depends-on] detected during build #6.

To unlock the merge button, you must

• Merge or close include sofa/core/fwd.h instead of the forward declaration Sofa.Qt#30
  For this build, the following CMake flags will be set
  -DSOFA_QT_GIT_REPOSITORY='https://github.com/sofa-framework/Sofa.Qt'
  -DSOFA_QT_GIT_TAG='18eb1108fc75996ebcf748711cd4990b6dabb54a'

[sofabot]

[ci-depends-on] detected during build #7.

To unlock the merge button, you must

• Merge or close include sofa/core/fwd.h instead of the forward declaration Sofa.Qt#30
  For this build, the following CMake flags will be set
  -DSOFA_QT_GIT_REPOSITORY='https://github.com/sofa-framework/Sofa.Qt'
  -DSOFA_QT_GIT_TAG='18eb1108fc75996ebcf748711cd4990b6dabb54a'

[sofabot]

[ci-depends-on] detected during build #8.

To unlock the merge button, you must

• Merge or close include sofa/core/fwd.h instead of the forward declaration Sofa.Qt#30
  For this build, the following CMake flags will be set
  -DSOFA_QT_GIT_REPOSITORY='https://github.com/sofa-framework/Sofa.Qt'
  -DSOFA_QT_GIT_TAG='a2435ca64136ea14f8d076f9f6a59678080860b2'

[sofabot]

[ci-depends-on] detected during build #9.

To unlock the merge button, you must

• Merge or close include sofa/core/fwd.h instead of the forward declaration Sofa.Qt#30
  For this build, the following CMake flags will be set
  -DSOFA_QT_GIT_REPOSITORY='https://github.com/sofa-framework/Sofa.Qt'
  -DSOFA_QT_GIT_TAG='a2435ca64136ea14f8d076f9f6a59678080860b2'

[sofabot]

[ci-depends-on] detected during build #10.

All dependencies are merged/closed. Congrats! 👍

[bakpaul]

[ci-build]

[sofabot]

[ci-depends-on] detected during build #11.

All dependencies are merged/closed. Congrats! 👍

[bakpaul]

BAck to review because scene tests have strange error not seen elsewhere.

[alxbilger]

I think the error you mention is

[ERROR]   [SofaPython3::SceneLoader] Unable to completely load the scene from file '/workspace/build/external_directories/fetched/SofaPython3/examples/access_mass_matrix.py'.  
Python exception:   
  TypeError: Unknown Attribute(s):   
  - Unable to set attribute 'ordering' with value: Natural. Possible misspelling of attribute 'orderingMethod' ?  


At:
  /workspace/build/external_directories/fetched/SofaPython3/examples/access_mass_matrix.py(61): createScene

which is fixed in sofa-framework/SofaPython3#577. Let's re-run the jobs and see...

[hugtalbot]

This PR deserves the attention of all @sofa-framework/reviewers

[sofabot]

[ci-depends-on] detected during build #12.

All dependencies are merged/closed. Congrats! 👍

[sofabot]

[ci-depends-on] detected during build #13.

All dependencies are merged/closed. Congrats! 👍

[bakpaul]

[ci-build][force-full-build]

[sofabot]

[ci-depends-on] detected during build #14.

All dependencies are merged/closed. Congrats! 👍