optimize and make sure unused-imports is accurate

[0xalpharush]

It was added in #2392 but it is really slow and has some edge cases e.g.
this is wrong

The following unused import(s) in src/universal/CrossDomainMessenger.sol should be removed:
        -import { Initializable } from "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol"; (src/universal/CrossDomainMessenger.sol#4)

slither contracts.zip --detect unused-import
contracts.zip

[0xalpharush]

@DarkaMaul Maybe you will have a chance to give this a go

[0xalpharush]

We may be able to use something like this to speed up the lookups
https://pypi.org/project/intervaltree/

Also, we could look into something like Rowan's red-green trees

[smartcontracts]

Yeah this would be great, we're looking to check for unused imports to keep things clean ethereum-optimism/optimism#11806