feat: add AYS(Align Your Steps) scheduler (#241)
Added NVIDEA's new "Align Your Steps" style scheduler in accordance with their
quick start guide. Currently has handling for SD1.5, SDXL, and SVD, using the
noise levels from their paper to generate the sigma values. Can be selected
using the --schedule ays command line switch. Updates the main.cpp help
message and README to reflect this option, also they now inform the user
of the --color switch as well.
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Co-authored-by: leejet <[email protected]>
