Update Seurat conversion with scpcaTools function

Currently we describe conversion to Seurat by giving several individual wrangling steps: https://scpca.readthedocs.io/en/latest/faq.html#what-if-i-want-to-use-seurat-instead-of-bioconductor

It may help to additionally tell users about `scpcaTools::sce_to_seurat()`, including instructions on installing this package and any associated package caveats.

Open the FAQ section linked in the issue and review the existing Seurat conversion guidance. Document scpcaTools::sce_to_seurat(), including how to install scpcaTools and any package caveats; done means users can follow the updated instructions to convert to Seurat.

Written by the indexing model from the issue text.