Adapt `RemoteExternalities` and its related types to be used with generic hash parameters (#3953)
Closes https://github.com/paritytech/polkadot-sdk/issues/3737 --------- Co-authored-by: command-bot <> Co-authored-by: Oliver Tale-Yazdi <[email protected]> Co-authored-by: Bastian Köcher <[email protected]>