[RPC-Spec-V2] chainHead: use integer for block index and adjust RuntimeVersion JSON format#1666

tadeohepperle merged 12 commits intomasterparitytech/polkadot-sdk:masterfrom

tadeohepperle/rpc-spec-v2-apis-as-map-and-index-as-numberparitytech/polkadot-sdk:tadeohepperle/rpc-spec-v2-apis-as-map-and-index-as-numberCopy head branch name to clipboard