Add support for managing Anvil instance

[ArtificialPB]

Module

Other

📝 Description

Support for managing Anvil instances used for testing. Should support the following:

• spawning on custom or random ports
• killing (+ shutdown hook auto-kill on exit if we're the ones spawning the instance)
• forking
• loading private keys on spawn
• configuring options
• anvil middleware with custom and special methods: https://book.getfoundry.sh/reference/anvil/#custom-methods

Example implementation: https://github.com/gakonst/ethers-rs/blob/master/ethers-core/src/utils/anvil.rs