* op-challenger: Remove duplicate validation for vm.Config instances

* op-challenger: Remove cannon-network and asterisc-network flags.

* op-challenger: Use vm flags for rollup-config and l2-genesis

* op-challenger: Deduplicate prestates URL parsing

* op-challenger: Remove legacy --cannon-l2 flag

* op-challenger: Show generic and trace type specific names in error messages.

* Update expected error messages.