Add configuraton for localnet default version

[epsjunior]

It should show the user the available versions so the user can choose

[HusseinAdeiza]

Taking this.

On v0.40-dev the flag still defaults to the hardcoded v0.65.0 and nothing lists what else is published, so discovery is still open. PR #424 reads the yeagerai/simulator-jsonrpc tags and offers them newest-first when no version is passed; an explicit --localnet-version is untouched, and offline/rate-limited/no-TTY all fall back to the current default.