A RPC handler to create sync states for light clients.
Currently only usable with BABE + GRANDPA.
Usage
To use the light sync state, it needs to be added as an extension to the chain spec:
use LightSyncStateExtension;
type ChainSpec = GenericChainSpec;
If the [LightSyncStateExtension] is not added as an extension to the chain spec,
the [SyncState] will fail at instantiation.