[TM-218] integrational testing engine confusing behavior

Description

Let's consider such a test:

  originate …
  transferA
  transferB
  validate $ Left …
  transferC
  validate …

Let's assume that originate and transferA succeed and transferB fails according to what the first validator expects. Then it seems natural that transferC will see effects of originate and tranferB, but it won't. All operations between to validators are batched and either all or none of them are applied. It looks somewhat confusing. This MR refactors integrational testing engine a little so it interprets operators as they added.

Related issue(s)

https://issues.serokell.io/issue/TM-218

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