Add `PaCMAP` to Seurat-Wrappers

[hyhuang00]

Dear Seurat-wrappers Developers,

We would like to add the PaCMAP algorithm to the Seurat Wrappers. This PR implements the RunPaCMAP() wrapper for the PaCMAP algorithm. The original implementation of the algorithm can be found at the current official repository. A detailed study on PaCMAP on scRNA-seq data can be found in our paper.

Best, Yiyang Sun, Haiyang Huang, Gaurav Rajesh Parikh, Cynthia Rudin