Clean up and split up `is_pre_funded_state`#4021

Merged

TheBlueMatt merged 3 commits intolightningdevkit:mainfrom

TheBlueMatt:2025-08-pre-funded-state-checks

Aug 28, 2025

Commits on Aug 28, 2025

Dont use `is_pre_funded_state` to short-circuit `shutdown` handling
TheBlueMatt
committed
Don't use `is_pre_funded_state` to provide an FC monitor update
TheBlueMatt
committed
Split out remaining uses of `is_pre_funded_state` and rename it
TheBlueMatt
committed