Currently the Solc input for all proxy-related contracts are packaged into one build-info.json file. When using this to verify source code on Etherscan, this causes the contracts for every different proxy kind to be included.

For example, even if the user is only using ERC1967Proxy, the source code for TransparentUpgradeableProxy would also be included in the verified source code.

To improve this, we should verify each proxy-related contract using its own Solc input for that contract and its dependencies only.