Rewrite world mocking

[Arjentix]

World mocking using WorldTrait is quite painful and causes some problems and inconsistency especially after merge of #2284

We need to find another way to mock World for tests.
Some solutions I can see right now:

1. Use mockall crate
2. Remove mocking at all and do some test runtime preparation using genesis, instructions and other supported things
3. Like 2 but use procedural macro for that

[appetrosyan]

The option 1. should be the first thing that we try. We don't want to maintain a separate non-compliant mocking library inside of Iroha. To me this is a relatively large change, so we should put this off until after the LTS is released.

The option 2 is something that we will need to do eventually, since test_network only crudely approximates the behaviour of a real system. I think that we need to have a lot more real integration tests, and improve the coverage with unit tests.