Add Stylus contracts support for Arbitrum

[rimrakhimov]

Support stylus github repository verification method on frontend. Currently backend supports stylus contracts verification on Arbitrum Sepolia instance. Corresponding endpoint - https://arbitrum-sepolia.blockscout.com/api/v2/smart-contracts/{contract_address}/verification/via/stylus-github-repository

Detailed description:
https://www.notion.so/blockscout/Verification-contracts-implemented-in-Rust-C-etc-f7efb784cf08497cbe5071a08db11523#c3e46647c11a4b22b882553b79a7b8b7