[V3]: refactor ComfyNodeV3 class; use of ui.SavedResult

[bigcat88]

1. Ported and tested the SaveAnimatedPNG and SaveAnimatedWEBP nodes.
2. The SavedResult class now inherits from dict, which greatly simplifies the code and its serialization, while still supporting the old-style usage with type checking.
3. Implemented detection of whether validate_inputs is defined in a child node by walking through the inheritance chain.
4. In additional commit, refactored the check for the check_lazy_status and fingerprint_inputs

This PR reduces the number of ruff warnings from 50+ to 19.