✨(gentest): make `gentest` great

[danceratopz]

The gentest CLI is a really nice tool that can generate and write a Python (pytest) test module to disk given a type 0 transaction hash on a live network. This generates a blockchain_test from the mainnet transaction 0xa41f...06be:

uv run gentest -c config.json 0xa41f343be7a150b740e5c939fa4d89f3a2850dbe21715df96b612fc20d1906be tests/paris/test_0xa41f.py

Currently, due to its limited transaction type support (type 0 only), it's of limited use. This meta ticket is to track progress of making gentest an easy-to-use CLI tool that can generate test cases for specific issues observed on devnets, and potentially, to allow benchmarking of an EVM's transaction processing using blockchain_tests created from real mainnet data.

While working on the issues below, we should consider and try to ensure that gentest also works on Verkle and EOF testnets.

### Tasks
- [ ] #859 
- [ ] #860
- [ ] #864
- [ ] #863
- [ ] #861 
- [ ] #862 
- [ ] #865