`chainSpec_lightSyncState`: Provide light-client sync state

What would be the most appropriate way to fetch the chain spec needed for the light-client with the new V2 APIs?

Although there's been some discussion about a standard format for this checkpoint

• https://github.com/paritytech/polkadot-sdk/issues/60
• https://github.com/paritytech/polkadot-sdk/issues/12

Ideally, we would stabilize the format of the sync-state before including it in the chainSpec class of functions.

Opening this to gather your opinion since we are also moving to stabilize the V1 of the chainSpec in

• https://github.com/paritytech/json-rpc-interface-spec/pull/59

Some advantages will be that

• we'll have the functionality needed to migrate the ecosystem to the RPC-V2 methods (Are you aware of any other methods we'd need 100% to keep parity with the old APIs?)
• the chainSpec will be versioned and V1 will always return the same result (would avoid breaking changes for smoldot as in - https://github.com/paritytech/substrate/pull/9284)

While in constant change, we might needlessly burn multiple chainSpec versions until we find a final syncState

// @paritytech/subxt-team