Add back methylation array and WGMS data support

[biobenkj]

This is a TODO and really needs to be done for full functionality. Reason for removing it initially is that the pre-print didn't focus on methylation data, but follow-up results do.

[QianhuiWan]

Hi Johnson, I hope this message finds you well. I wanted to kindly ask if the getABSignal() function also works for WGBS data. Thank you so much for your help!
Best regards,
Qianhui