feature request: Bundle sources for all addresses in tx's trace

`seth run-tx` will bundle the source of the entrypoint contract called in the tx it's given by default now.

However for upgradable proxies, or just more complex txs that interact with many contracts, we need bundled sources for more than just the entrypoint.

Ideally we could have run-tx do a first pass trace without bundled sources, identify all contracts that can have their sources bundled and put them into one mega file that run-tx parses on its second pass and pretty-prints with function names, etc