Add PoE Extrinsics to Blocks

The Proof Of Existence Pallet is fully integrated into your runtime at this point, but we aren't really using it.

Create some new Blocks in your fn main() to test out the functionality of the Proof of Existence Pallet.

Be creative, and even feel free to introduce some extrinsics which will trigger errors based on the logic of your pallets.

Don't forget to increment your block number and actually call execute_block for each of those blocks.

Take a look at the final output and check that the state of your machine makes sense!