Add workaround in validation.py for V3 Combo outputs (only merge after stable)

[Kosinkadink]

To make V3 Combo work as outputs in the frontend, we provide the list of options as the output io_type. This does not jive well with the current logic of validation and makes me question how it worked for V1, so I added code to treat a tuple of values as COMBO.

[Lex-DRL]

Works for me. Tested on the same debug example + a couple of nodes from here: https://github.com/Lex-DRL/ComfyUI-BestResolution/tree/dev