Add support for setting the 'scheduler' type needed for webui 1.9

[skfoo]

Recent version of Auto1 (starting with 1.9?) split the Sampler into two fields, Sampler and Scheduler. If you have grids that used 'DPM 2M Karras', you now need to specify two parameters to make it work (Sampler=DPM 2M and Scheduler=Karras).

I've been too lazy to do anything about it and just started using the Restart sampler...

The sd webui's xyz_grid.py has the info needed for supporting Scheduler (field is 'scheduler' and possible values are modules/sd_scheduler's 'schedulers' property).