community[minor]: Add Datahareld tool (#19680)

**Description:** Integrate [dataherald](https://www.dataherald.com)
tool, It is a natural language-to-SQL tool.
**Dependencies:** Install dataherald sdk to use it,
```
pip install dataherald
```

---------

Co-authored-by: Bagatur <22008038+baskaryan@users.noreply.github.com>
Co-authored-by: Bagatur <baskaryan@gmail.com>
Co-authored-by: Christophe Bornet <cbornet@hotmail.com>

libs/community/langchain_community/utilities/dataherald.py

@@ -0,0 +1,67 @@
+"""Util that calls Dataherald."""
+from typing import Any, Dict, Optional
+
+from langchain_core.pydantic_v1 import BaseModel, Extra, root_validator
+from langchain_core.utils import get_from_dict_or_env
+
+
+class DataheraldAPIWrapper(BaseModel):
+    """Wrapper for Dataherald.
+
+    Docs for using:
+
+    1. Go to dataherald and sign up
+    2. Create an API key
+    3. Save your API key into DATAHERALD_API_KEY env variable
+    4. pip install dataherald
+
+    """
+
+    dataherald_client: Any  #: :meta private:
+    db_connection_id: str
+    dataherald_api_key: Optional[str] = None
+
+    class Config:
+        """Configuration for this pydantic object."""
+
+        extra = Extra.forbid
+
+    @root_validator()
+    def validate_environment(cls, values: Dict) -> Dict:
+        """Validate that api key and python package exists in environment."""
+        dataherald_api_key = get_from_dict_or_env(
+            values, "dataherald_api_key", "DATAHERALD_API_KEY"
+        )
+        values["dataherald_api_key"] = dataherald_api_key
+
+        try:
+            import dataherald
+
+        except ImportError:
+            raise ImportError(
+                "dataherald is not installed. "
+                "Please install it with `pip install dataherald`"
+            )
+
+        client = dataherald.Dataherald(api_key=dataherald_api_key)
+        values["dataherald_client"] = client
+
+        return values
+
+    def run(self, prompt: str) -> str:
+        """Generate a sql query through Dataherald and parse result."""
+        from dataherald.types.sql_generation_create_params import Prompt
+
+        prompt_obj = Prompt(text=prompt, db_connection_id=self.db_connection_id)
+        res = self.dataherald_client.sql_generations.create(prompt=prompt_obj)
+
+        try:
+            answer = res.sql
+            if not answer:
+                # We don't want to return the assumption alone if answer is empty
+                return "No answer"
+            else:
+                return f"Answer: {answer}"
+
+        except StopIteration:
+            return "Dataherald wasn't able to answer it"