EIP-7951 P256verify Precompiles

Documentation for tests/osaka/eip7951_p256verify_precompiles@7b8124a7.

Generate fixtures for these test cases for Bpo2 with:

fill -v tests/osaka/eip7951_p256verify_precompiles --fork Bpo2

Tests EIP-7951: Precompile for secp256r1 Curve Support.