✨(gentest): create blockchain_test test cases from multiple transaction hashes or block hash

[danceratopz]

Add support to create blockchain_test tests cases. This idea will need some speccing out.

A blockchain_test (consisting of one block) could potentially be created from a list of transaction hashes (useful?) or, from a single or multiple block hashes. The latter idea originated from @chfast in order to benchmark EVM using real mainnet data (from the R&D Discord).

How do we handle a block that contains type 3 transactions?