Polkadot Testnet RPC gas estimation

[albertov19]

Motivation

Polkadot is rolling out a REVM backend, but it requires custom gas mapping so gas estimation needs to be done via RPC.

Solution

Adds Polkadot as a named chain that needs gas estimation via RPC call. Goes with https://github.com/alloy-rs/chains/pull/222

PR Checklist

• [ ] Added Tests
• [ ] Added Documentation
• [ ] Breaking changes

[grandizzy]

lgtm, @albertov19 OK to move in ready for review / merge? thanks!

[albertov19]

Thanks for the quick turnaround - the REVM backend should be ready next week. I'll mark it ready for review and ping you all by then. You were too quick 😅