convert AlignYourStepsScheduler node to V3 schema

[bigcat88]

This node is widely used by the community in these three ways:

if scheduler.startswith('AYS'):
    sigmas = nodes.NODE_CLASS_MAPPINGS['AlignYourStepsScheduler']().get_sigmas(scheduler[4:], steps, denoise=1.0)[0]
else:
   sigmas = samplers.calculate_sigmas(model.get_model_object("model_sampling"), scheduler, steps)

from comfy_extras.nodes_align_your_steps import AlignYourStepsScheduler

model_type = scheduler.split(' ')[1]
sigmas = AlignYourStepsScheduler().get_sigmas(model_type, steps, denoise)[0]

sigmas = nodes_align_your_steps.AlignYourStepsScheduler.get_sigmas(self, model_type, steps, denoise)
sampler = comfy.samplers.sampler_object(sampler_name)

All of these variants were tested with this PR.

Why is get_sigmas not defined as follows in this PR:

def get_sigmas(self, model_type, steps, denoise):
        return self.execute(model_type, steps, denoise).result

This is because one of the community's usage variants will result in an AttributeError: 'AlignYourStepsSchedule' object has no attribute 'execute'. This error occurs because community nodes pass their own class as self, which is not the AlignYourStepsScheduler and does not have get_sigmas defined. The original AlignYourStepsScheduler.get_sigmas from the V1 schema does not use self, which is why it works for the community.

---

Question: Should we add a clear RuntimeWarning to get_sigmas, like this:

warnings.warn(
            "get_sigmas() is deprecated; please switch to the V3 schema and call .execute(...) directly",
            DeprecationWarning,
            stacklevel=2,
        )