Breaking changes: major reorganization of netneurotools

[liuzhenqi77]

Overall tasks

• Reorganize the package structure
• Add some new functions and migrate some functions
• Fix deprecations, warnings, etc., and try to remove some dependencies
• Fix/update some package settings

New functions

• fetch project-related datasets
• pyvista plotting
• spatial & stats

Migrate functions

• spin-related

Remove dependencies

• bctpy

Optional new dependencies

• pyvista

[liuzhenqi77]

Currently the major changes are:

Complete reorganization of the package structure

• new modules, new functions, new docs

Updated datasets module

Fixed styles with ruff