The node attribue scratchpad_state is not in sway

[sophacles]

The attr scratchpad_state is not present in ipc output of sway. It's unclear if it ever was there, but the last occurance of the string scratchpad_state in the sway repo was removed in this commit:

swaywm/sway@a6bc46e

The attribute should probably be gated the sway feature flag.

[sophacles]

@leshow Im working on getting a project I have to work with sway as well as i3, I'm fine putting up a PR for this. I presume similar things may be discovered over the next few days as I work on it. Would you prefer if I make this ticket a general "sway differences" ticket or do a separate one (and pr) for each?

(I'm happy to do this work either way though :) )

[leshow]

Hey! Yes, I'd prefer it all in one PR. Feature gating the sway fields sounds good!