Migrate the MVP into kotaemon (#108)

- Migrate the MVP into kotaemon.
- Preliminary include the pipeline within chatbot interface.
- Organize MVP as an application.

Todo:

- Add an info panel to view the planning of agents -> Fix streaming agents' output.

Resolve: #60
Resolve: #61 
Resolve: #62

pyproject.toml

@@ -16,6 +16,7 @@ requires-python = ">= 3.10"
 description = "Kotaemon core library for AI development."
 dependencies = [
     "langchain",
+    "langchain-community",
     "theflow",
     "llama-index>=0.9.0",
     "llama-hub",
@@ -56,7 +57,6 @@ dev = [
     "python-dotenv",
     "pytest-mock",
     "unstructured[pdf]",
-    # "farm-haystack==1.22.1",
     "sentence_transformers",
     "cohere",
     "elasticsearch",