Update block fields check to use current vm's block header

[fselmo]

What was wrong?

• This is a minor change that is nice to have but also necessary for full web3.py <-> eth-tester <-> py-evm support in order to update fields that are meant to be coming from the consensus layer.

Bonus: Instead of just copying the messages from the EIP, provider values in the error message when the calculated blob_gas_used doesn't match the block header blob gas used. This kind of helped track this down but also is just a nicety :)

How was it fixed?

• Use the current vm's header to check fields got vm.pack_block()

Todo:

• Clean up commit history
• Add entry to the release notes

Cute Animal Picture

[kclowes]

looks good to me!