Advanced Tutorials for using relax.methods

[BirkhoffG]

Extending tutorials/methods.ipynb by adding another section to explain the advanced usage of CFModule.apply_constraints.

Delivery

1. Add another section after "Config Recourse Methods". The title can be something like "Advanced Usage", but you can decide a better title.
2. Explain why we need apply_constraints. Check out this.
3. Explain how to set_apply_constraints_fn, and give an example.