Reading old chain state + example usage

[Lezek123]

yarn workspace @joystream/js-examples build
yarn workspace @joystream/js-examples run-example readOldState

We can also provide endpoint and block number (which was before Contantinopole => Nicaea upgrade in that case)

yarn workspace @joystream/js-examples run-example readOldState wss://rome-rpc-endpoint.joystream.org:9944/ 1500000
yarn workspace @joystream/js-examples run-example readOldState ws://localhost:3000/ 50

Feedback about more interesting cases of querying old chain data that could be tested with this script will be much appreciated.

[Lezek123]

This is no longer relevant since the much newer version of @polkadot/api we're using now exposes functionality like api.at (polkadot-js/api#3871) for this purpose.