API: create dataset

[JinHai-CN]

What problem does this PR solve?

This PR have finished 'create dataset' of both HTTP API and Python SDK.
HTTP API:

curl --request POST --url http://<HOST_ADDRESS>/api/v1/dataset   --header 'Content-Type: application/json' --header 'Authorization: <ACCESS_KEY>' --data-binary '{
  "name": "<DATASET_NAME>"
}'

Python SDK:

from ragflow.ragflow import RAGFLow
ragflow = RAGFLow('<ACCESS_KEY>', 'http://127.0.0.1:9380')
ragflow.create_dataset("dataset1")

TODO:

• ACCESS_KEY is the login_token when user login RAGFlow, currently. RAGFlow should have the function that user can add/delete access_key.

Type of change

• New Feature (non-breaking change which adds functionality)
• Documentation Update