WIP - Lazy loading

[RomarQ]

What does it do?

polkadot-sdk companion: https://github.com/moonbeam-foundation/polkadot-sdk/tree/rq/lazy-loading

What important points reviewers should know?

Is there something left for follow-up PRs?

What alternative implementations were considered?

Are there relevant PRs or issues in other repositories (Substrate, Polkadot, Frontier, Cumulus)?

What value does it bring to the blockchain users?