Refactor agents and tools (#91)

* Move tools to agents

* Move agents to dedicate place

* Remove subclassing BaseAgent from BaseTool

knowledgehub/agents/tools/llm.py

@@ -0,0 +1,34 @@
+from typing import AnyStr, Optional, Type, Union
+
+from pydantic import BaseModel, Field
+
+from kotaemon.llms import LLM, AzureChatOpenAI, ChatLLM
+
+from .base import BaseTool, ToolException
+
+BaseLLM = Union[ChatLLM, LLM]
+
+
+class LLMArgs(BaseModel):
+    query: str = Field(..., description="a search question or prompt")
+
+
+class LLMTool(BaseTool):
+    name = "llm"
+    description = (
+        "A pretrained LLM like yourself. Useful when you need to act with "
+        "general world knowledge and common sense. Prioritize it when you "
+        "are confident in solving the problem "
+        "yourself. Input can be any instruction."
+    )
+    llm: BaseLLM = AzureChatOpenAI()
+    args_schema: Optional[Type[BaseModel]] = LLMArgs
+
+    def _run_tool(self, query: AnyStr) -> str:
+        output = None
+        try:
+            response = self.llm(query)
+        except ValueError:
+            raise ToolException("LLM Tool call failed")
+        output = response.text
+        return output