Feature Request: Pad Prompts to same length token length/window

Certain diffusion methods such as AnimateDiff suffer greatly with prompts of differing token lengths, making it virtually impossible to use popular textual inversions/embeddings in the negative prompt. [Auto1111 has this setting, which is implemented here](https://github.com/AUTOMATIC1111/stable-diffusion-webui/blob/5ef669de080814067961f28357256e8fe27544f4/modules/sd_samplers_cfg_denoiser.py#L149C15-L149C15). It would be nice for this to be in the base KSampler node. I'm fairly unfamiliar with the codebase, but would love to try implementing it myself in a custom node or here. Where would I find code equivalent to auto's sd_samplers_cfg_denoiser.py in comfyui's codebase?