Implement utility function DetermineNewBlocks

## Issue summary

- Some of the subsystems use a utility function DetermineNewBlocks to determine new blocks that we should track metadata for.
- A stub for this function was created here: https://github.com/ChainSafe/gossamer/blob/0dcd13fc6c7d6e26c8fbd5a3a7c238aefe13d139/dot/parachain/util/util.go#L69
- This issue is to complete this function.

## Other information and links

- See polkadot implementation: https://github.com/paritytech/polkadot-sdk/blob/aa68ea58f389c2aa4eefab4bf7bc7b787dd56580/polkadot/node/subsystem-util/src/determine_new_blocks.rs#L34