refactor: use same code path and config for Solidity test runner integration tests

[agostbiro]

This PR achieves to goal set out in #607 to use same code path and config for Solidity test runner integration tests. It does this by

1. Allowing only one way to construct the Rust test runner (MultiContractRunner::new).
2. Constructing the Rust test runner with the SolidityTestRunnerConfig that previously resided in edr_napi, instead of foundry_config::Config.

foundry_config::Config has been renamed to foundry_config::IntegrationTestConfig as some fields of it are still needed to build the Rust integration tests as a Foundry project. The rest of its functionality has been removed. I kept the foundry_config crate for now to be able to track the changes.

The PR doesn't contain any non-trivial code changes, so for me the most helpful would be to review it to see if anything has been removed that shouldn't be removed.

[changeset-bot]

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Latest commit: 0258c35

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