feat: set up env for test & add basic unit test example

[0xSulpiride]

Description

• added basic unit test for ReputationService, UserOpValidationService and EthModule
• tests are run by "npm run test"
• Tests use Anvil so in order to run them you must have Anvil installed - https://book.getfoundry.sh/getting-started/installation

Types of changes

What types of changes does your code introduce? Put an x in the boxes that apply

• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Documentation Update
• [ ] Code style update (formatting, renaming)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] Other (please describe):

Further comments (optional)

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[0xSulpiride]

Apparently viem library does not carry it's own evm for tests, it makes use of anvil or hardhat. We can use that with ethers.js as well, so I went on using Ethers in tests. To run tests you must have Anvil installed: https://book.getfoundry.sh/getting-started/installation

Also added some tests for UserOpValidationService and EthModule

[0xSulpiride]

I'll add some more unit tests for each module and service