* Copy-Pasta Call code from mock Rococo to mock Westend runtime

* Update Westend client to include signing and call related code

* Add missing part of license header

* Move `account_info_storage_key` to `polkadot-core` crate

* Implement fake rococo runtime.

* Generate correct storage key.

* cargo fmt --all

* Move client-rococo.

* Satisfy clippy.

* Apply suggestions from code review

Co-authored-by: Hernando Castano <[email protected]>

* Address review comments.

* Clippy again.

Co-authored-by: Hernando Castano <[email protected]>