node: extract shared init and shutdown helpers for run commands

[rishavmehra]

This refactor removes a lot of repeated code from runVerifyRange and runLive.
Both functions were doing the same setup and cleanup work, so that logic is now shared
The common parts include setting up the arena, starting the RPC server and checking the port creating block fetch options, building the shutdown context from replay results, updating state files with history and printing the shutdown summary when needed

By moving this shared logic into helpers, the code is easier to read and maintain
It also reduces the chance of bugs caused by the two functions getting out of sync

[rishavmehra]

@smcio can you review this!

[smcio]

hey @rishavmehra - nice, thanks very much. I'll review this later today :)