MSFDG: adapt AttackV2 and StepV2 functions in op-challenger2 and alphabet E2E test

[dajuguan]

Description:

• Adapt AttackV2 and StepV2 functions in op-challenger2
• Add tests cased for the above functions in op-challenger2/game/fault/solver/solver_test.go and op-challenger2/game/fault/solver/game_solver_test.go
• Integrate op-challenger2 and finish alphabet E2E test

Tests

• op-challenger2: all tests passed

  cd op-challenger2
  go test ./...

• alphabet game E2E: all tests passed

  cd op-e2e2
  go test -run '^(TestOutputAlphabetGame_ChallengerWins|TestOutputAlphabetGame_ReclaimBond|TestOutputAlphabetGame_ValidOutputRoot|TestChallengerCompleteExhaustiveDisputeGame|TestOutputAlphabetGame_FreeloaderEarnsNothing|TestHighestActedL1BlockMetric)$' [github.com/ethereum-optimism/optimism/op-e2e2/faultproofs](http://github.com/ethereum-optimism/optimism/op-e2e2/faultproofs)

[blockchaindevsh]

The description is too short for such a large change set IMO, could you elaborate in more detail so that the review can be easier?

[dajuguan]

The description is too short for such a large change set IMO, could you elaborate in more detail so that the review can be easier?

Considering the extensive context, it might be better to split the changes into multiple PRs during a future rebase. For now, I suggest focusing on reviewing cosmetic aspects like naming and variable conventions, as that seems more feasible.