🪚 OmniGraph™ Signing a transaction

[janjakubnanista]

In this PR

• Moving the most generic types to a utils package. This name seems a bit generic but it follows the naming convention
• Moving some of the arbitraries to test-utils. it would be nice to have them typed but that would create a dependency cycle - if test-utils depend on the types from utils and we want to use test-utils to test utils, we in trouble. However, this being a testing package, we don't care
• Creating the first draft of OmniSigner interface and an EVM implementation
• Use this signer implementation to enlarge the testing suite - new test has been added for configureOApp that now checks whether the function ignores the peers that have already been set