feat: support timeboost

[alxdca]

Summary

• Adds optional Timeboost support to CLI and GitHub Action testnode launches.
• Wires timeboostEnabled / timeboost-enabled through start config parsing, action inputs, testnode state, and Docker run args.
• Enables Nitro Timeboost sequencer args and exposes the timeboost,auctioneer HTTP APIs when the flag is enabled.
• Adds unit coverage for CLI defaults/config parsing, action state propagation, and Docker arg generation.

Why / Context

• Consumers need a first-class flag for starting published testnode images with Timeboost enabled.
• The flag defaults to false, preserving existing startup behavior unless users explicitly opt in.