Arbitrum v2.0.0 Nitro Beta 1

This release breaks compatibility with the old devnet and adds support for a new anytrust network.

User-facing Improvements

• Add a new node interface method for splitting gas estimation results into their component parts: #648
• Add extra fields to tracing to track transfers done outside of EVM execution: #664
• Add an isSpent method to the outbox: #720

Internal Highlights

• At-cost L1 gas pricing: #585
• Wasm testsuite: #586
• feat: efficient merkleprooflib saves 100s gas: #624
• Change retryable refund calculation: #654
• Remove old ArbOS versions and their behaviors: #683
• Genesisblock in chainconfig and arbos-state: #691
• Add new anytrust chain config defaults: #721

Full Changelog: v2.0.0-alpha.5...v2.0.0-beta.1