[Mercedes-AMG] Check Test Case Spec consistency

[msauren]

Description

As a test script developer I want to have consistent and structured Action blocks.

Expected Behaviour

• the custom check should fail if the top level block 'Action' of a test case .pkg has other test steps than
  'TsBlock' in it's first 2 hierarchy levels.

Additional Information

For us the typical 'Action' block will look like this:

• Block: Action
  • Block: Step 1
    • Block: Press accelerator pedal 50 %
      • PackageCall: ...
    • Block: Wait until velocity exceeds 100 km/h
      • Read: ... (wait until)