Torch-harmonics

* Adding github CI
* Changed SHT modules to convert dtype dynamically when computing the SHT/ISHT
* Bugfixes to fix importing examples

* Minor bugfixes to export SFNO code
* Readme should now render correctly in PyPI

* Added SFNO example
* Added Shallow Water Equations Dataset for SFNO training
* Cleanup of the repository and added PyPI
* Updated Readme

* Reworked distributed SHT
* Module for sampling Gaussian Random Fields on the sphere

* Computation of associated Legendre polynomials
* changed algorithm to compute the associated Legendre polynomials for improved stability
* Improved Readme

* Vector Spherical Harmonic Transforms
* projects vector-valued fields onto the vector Spherical Harmonics
* supports computation of div and curl on the sphere
* New quadrature rules
* Clenshaw-Curtis quadrature rule
* Fejér quadrature rule
* Legendre-Gauss-Lobatto quadrature
* New notebooks
* complete with differentiable Shallow Water Solver
* notebook on quadrature and interpolation
* Unit tests
* Refactor of the API