v2.1.0 - Arbitrum bridge and L2 support

What's Changed

• gre: refactor to allow using L1 and L2 simultaneously by @tmigone in #682
• fix: ensure GRE handles multiple chains with same chainId gracefully by @tmigone in #695
• fix: prevent underflow when subgraphs go under the minimum signal threshold by @pcarranzav in #640
• Sync: l2-testnet / scenario1 > dev by @tmigone in #703
• chore: add e2e tests to github workflows by @tmigone in #663
• chore: add GRE test to GitHub actions by @tmigone in #706
• feat(gre): desambiguate chainIds using secondary network name by @tmigone in #714
• feat(gre): add wallet methods by @tmigone in #716
• some improvements in config files by @pcarranzav in #679
• ci: run e2e on local nitro node by @pcarranzav in #711
• feat(cli): add publish and mint using multicall by @abarmat in #713
• chore: add reports for recent audits by @pcarranzav in #710
• L2 bridge: safer callhook interface by @pcarranzav in #719
• Run GitHub actions only when it makes sense by @tmigone in #707
• chore: provide sane defaults for graph config (dev branch) by @tmigone in #721
• chore: remove rinkeby and kovan by @tmigone in #729
• feat: add optional expression logging to GRE by @tmigone in #728
• test: fix race condition in BridgeEscrow tests by @pcarranzav in #730
• chore: provide sane defaults for graph config (l2-bridge branch) re-#722 by @tmigone in #727
• test: don't use nc to check if evm is running by @pcarranzav in #731
• test: print gas report, and ensure evm is killed by @pcarranzav in #732
• feat(gre): add hardhat-secure-accounts to GRE by @tmigone in #696
• fix: prevent unpausing gateways if they're not configured (OZ M-01 from #700) by @pcarranzav in #733
• fix: validate Arbitrum addresses and callhook senders are contracts (OZ L-01 from #700) by @pcarranzav in #734
• fix: remove unnecessary L2 gas check (OZ N-01 from #700) by @pcarranzav in #735
• fix: add storage gaps to GraphTokenGateway and GraphTokenUpgradeable (C4 M-244) by @pcarranzav in #739
• fix: ensure l2Counterpart is nonzero (C4 M-201) by @pcarranzav in #740
• fix: ensure contracts are only initialized once (C4 M-149) by @pcarranzav in #741
• c4: gas optimization fixes by @tmigone in #742
• C4 QA fixes for #699 by @pcarranzav in #743
• fix: remove unneeded empty bytes from callhook data by @pcarranzav in #745
• fix(L1GraphTokenGateway): add a counterpartGateway getter for Router compatibility by @pcarranzav in #748
• L2 public testnet deployment and related fixes by @pcarranzav in #751
• feat(e2e): deploy and configure both layers with the e2e script by @tmigone in #717
• feat: add Arbitrum GRT bridge (rebased, bridge only) by @pcarranzav in #699
• feat: added tasks to list bridge txs by @tmigone in #755
• L2 deployment release and configuration by @abarmat in #756

Full Changelog: v1.16.0...v2.1.0