Feature Request: Cache fetched source code during on-chain fuzzing for reuse in subsequent runs

[rappie]

Describe the desired feature

Fetching source for 0x14716C982Fd8b7F1E8F0c4dbb496dCe438a29D93 from Sourcify... Success!

This now happens after every run, which is a lot when debugging. It would be great if we can cache this.

[gustavo-grieco]

If you don't need the coverage report from the on-chain contracts, use --disable-onchain-sources.