Use sgkit.distarray for PCA

[tomwhite]

More progress on #908

This needs cubed-dev/cubed#598 which hasn't been merged yet

[tomwhite]

This is working, now that SVD for Cubed has been merged.

This change involves adding a copy of TruncatedSVD from Dask-ML, suitably modified to support the Array API, as well as Dask. Since this was the only code we use from Dask-ML it allows us to remove the Dask-ML dependency.

In the future we may be able to remove the copy of TruncatedSVD entirely, and use the original from scikit-learn - but only once it has been converted to be Array API compatible (note that regular PCA has already been converted).

[jeromekelleher]

Looks great - num_dependencies -= 1!