feat(models): Added ExtractModel

ExtractModel helps to extract data from the server response
class ExtractModel:
    name: str            # Name of data
    json_path: str       # Name of field in data
    source: str          # Source of data

models/itm.py

@@ -8,6 +8,12 @@ class RequestModel(BaseModel):
     timeout: int = 30
 
 
+class ExtractModel(BaseModel):
+    name: str
+    json_path: str
+    source: str = "body"
+
+
 class StepModel(BaseModel):
     name: str
     request: RequestModel