API: Add preset listing for sampler overrides

Querying the overrides list endpoint now returns the selected preset
and a list of presets to use.

Signed-off-by: kingbri <bdashore3@proton.me>

endpoints/OAI/types/sampler_overrides.py

@@ -1,5 +1,13 @@
 from pydantic import BaseModel, Field
-from typing import Optional
+from typing import List, Optional
+
+from common.sampling import SamplerOverridesContainer
+
+
+class SamplerOverrideListResponse(SamplerOverridesContainer):
+    """Sampler override list response"""
+
+    presets: Optional[List[str]]
 
 
 class SamplerOverrideSwitchRequest(BaseModel):