[Feature Request]: Add an option to use CPU only for VAE

[silvertuanzi]

Is there an existing issue for this?

• [X] I have searched the existing issues and checked the recent builds/commits

What would your feature do ?

For some very low GPU, it's OK when progressing but get out of memory when coming to VAE encode/decode. Since the Tiled VAE extension have solved this problem, this extension isn't work well in some case (for example, it produce grey block on directml). So it may be better to have an option to use CPU on VAE.

Proposed workflow

1. add command_line_args like "--use-cpu vae-encode" "--use-cpu vae-decode" "--use-cpu vae"
2. use CPU for vae encode or decode or both.

Additional information

No response