EIP-3855 Push0

Documentation for tests/shanghai/eip3855_push0.

Generate fixtures for these test cases with:

fill -v tests/shanghai/eip3855_push0

abstract: Tests EIP-3855: PUSH0 Instruction

Tests for [EIP-3855: PUSH0 Instruction](https://eips.ethereum.org/EIPS/eip-3855).