Run solidity tests in CI

[Stebalien]

I.e., the tests in https://github.com/filecoin-project/ref-fvm/tree/fc6547afef2c258a96549438b6e5bcacb0f2d403/tools/solidity-tests.

To do this, we'll need to make sure we can run these quickly. That'll likely require actor caching, at least, to avoid having to pay the wasm compile time for each test.