Split bucketfs into Multiple Modules

[Nicoretti]

The bucketfs package has been restructured to better accommodate future features. The primary change is the modification of __init__.py to serve as the main point for exposing the public interface of the bucketfs package through exasol.bucketfs. All other components have been relocated to private modules, with their public elements made accessible via __init__.py.

Important Notice for Developers:
This reorganization requires careful attention to imports to prevent circular dependencies within the private modules.

[ckunki]

Is there a changes file describing the changes?
Do we need to notify end users / developers about the changed packages?