Arbitrum support on Defender

Hey everyone! We have just enabled Arbitrum support on Defender, both for Arbitrum Mainnet and its Rinkeby-based testnet. You can now use Admin, Relayers, and Sentinels for managing contracts, sending transactions, and monitoring calls on both networks.

Note that Gnosis Safe creation is disabled for the time being, as the Gnosis team is still testing support of their contracts on the network.