feat(Mocking): make it easier to match any input in mockito

[bai-uipath]

This PR makes it easier to set up Mockito deterministic mocks in the case where we want it to always return a constant value (probably the most common case in practice).

Current design - explicit matching required using mockito.matchers.Any

  {                                                                                                                                       
    "function": "my_tool",                                                                                                                
    "arguments": {                                                                                                                        
      "kwargs": {                                                                                                                         
        "param1": {"_target_": "mockito.matchers.Any"},                                                                                   
        "param2": {"_target_": "mockito.matchers.Any"}                                                                                    
      }                                                                                                                                   
    },                                                                                                                                    
    "then": [{"type": "return", "value": "result"}]                                                                                       
  }

Improved design: arguments is optional, if omitted, always match

  {                                                                                                                                       
    "function": "my_tool",                                                                                                                
    "then": [{"type": "return", "value": "result"}]                                                                                       
  }

[akshaylive]

This would've been supported in this PR but I like your idea of defaulting it to ARGS, KWARGS.

Please rebase/bump version before merging.