Command reordering in Core

What was changed

Update core
Have .NET command-reorder behavior only apply if replaying with that flag (i.e. no longer apply and set the flag for new executions)
Removed internal-for-test-use-only option to disable .NET reordering
Add tests for post-completion commands including replays for pre-.NET-flag, post-.NET-flag, and current (post-Core-flag)
Add tests for multi-completion success first including replays for pre-.NET-flag, post-.NET-flag, and current (post-Core-flag)
Add tests for multi-completion failure first including replays for pre-.NET-flag, post-.NET-flag, and current (post-Core-flag)