This PR includes several improvements to Hardhat Network (PRs: #1083, #1086, #1100).
Most of these changes are internal and backward compatible. The exception is #1083, which changes the chainId used by the forked Hardhat Network. Before this version, when you forked the mainnet the chain id used was 1. Now it will use the default chain id (31337). You can change this via the Hardhat Network config.
Besides that, the names of the build info files are now deterministic (#1090).