### What problem does this PR solve?

discuss：#1102

#### Completed
1. Integrate API Flask to generate Swagger API documentation, through
http://ragflow_host:ragflow_port/v1/docs visit
2. Refactored http_token_auth
```
class AuthUser:
    def __init__(self, tenant_id, token):
        self.id = tenant_id
        self.token = token

    def get_token(self):
        return self.token


@http_token_auth.verify_token
def verify_token(token: str) -> Union[AuthUser, None]:
    try:
        objs = APIToken.query(token=token)
        if objs:
            api_token = objs[0]
            user = AuthUser(api_token.tenant_id, api_token.token)
            return user
    except Exception as e:
        server_error_response(e)
    return None

# resources api
@manager.auth_required(http_token_auth)
def get_all_datasets(query_data):
	....
```
3. Refactored the Datasets (Knowledgebase) API to extract the
implementation logic into the api/apps/services directory

![image](https://github.com/user-attachments/assets/ad1f16f1-b0ce-4301-855f-6e162163f99a)
4. Python SDK, I only added get_all_datasets as an attempt, Just to
verify that SDK API and Server API can use the same method.
```
from ragflow.ragflow import RAGFLow
ragflow = RAGFLow('<ACCESS_KEY>', 'http://127.0.0.1:9380')
ragflow.get_all_datasets()
```
5. Request parameter validation, as an attempt, may not be necessary as
this feature is already present at the data model layer. This is mainly
easier to test the API in Swagger Docs service
```
class UpdateDatasetReq(Schema):
    kb_id = fields.String(required=True)
    name = fields.String(validate=validators.Length(min=1, max=128))
    description = fields.String(allow_none=True)
    permission = fields.String(validate=validators.OneOf(['me', 'team']))
    embd_id = fields.String(validate=validators.Length(min=1, max=128))
    language = fields.String(validate=validators.OneOf(['Chinese', 'English']))
    parser_id = fields.String(validate=validators.OneOf([parser_type.value for parser_type in ParserType]))
    parser_config = fields.Dict()
    avatar = fields.String()
```

#### TODO

1. Simultaneously supporting multiple authentication methods, so that
the Web API can use the same method as the Server API, but perhaps this
feature is not important.
I tried using this method, but it was not successful. It only allows
token authentication when not logged in, but cannot skip token
authentication when logged in 😢
```
def http_basic_auth_required(func):
    @wraps(func)
    def decorated_view(*args, **kwargs):
        if 'Authorization' in flask_request.headers:
            # If the request header contains a token, skip username and password verification
            return func(*args, **kwargs)
        if flask_request.method in EXEMPT_METHODS or current_app.config.get("LOGIN_DISABLED"):
            pass
        elif not current_user.is_authenticated:
            return current_app.login_manager.unauthorized()

        if callable(getattr(current_app, "ensure_sync", None)):
            return current_app.ensure_sync(func)(*args, **kwargs)
        return func(*args, **kwargs)

    return decorated_view
```
2. Refactoring the SDK API using the same method as the Server API is
feasible and constructive, but it still requires time
I see some differences between the Web and SDK APIs, such as the
key_mapping handling of the returned results. Until I figure it out, I
cannot modify these codes to avoid causing more problems

```
    for kb in kbs:
        key_mapping = {
            "chunk_num": "chunk_count",
            "doc_num": "document_count",
            "parser_id": "parse_method",
            "embd_id": "embedding_model"
        }
        renamed_data = {}
        for key, value in kb.items():
            new_key = key_mapping.get(key, key)
            renamed_data[new_key] = value
        renamed_list.append(renamed_data)
    return get_json_result(data=renamed_list)
```

### Type of change

- [x] Refactoring

…request data schema (#2480)

### What problem does this PR solve?

- fixed documentss API request data schema
- add documents sdk api tests

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

### What problem does this PR solve?

1. Fixed swagger docs error in nginx external port
2. Add retrieval api
3. Add documentation for SDK API

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)
- [x] Documentation Update
- [x] Refactoring

### What problem does this PR solve?

1. Split SDK class to optimize code structure
`ragflow.get_all_datasets()`  ===>     `ragflow.dataset.list()`
2. Fixed the parameter validation to allow for empty values.
3. Change the way of checking parameter nullness, Because even if the
parameter is empty, the key still exists, this is a feature from
[APIFlask](https://apiflask.com/schema/).

`if "parser_config" in json_data` ===> `if json_data["parser_config"]`


![image](https://github.com/user-attachments/assets/dd2a26d6-b3e3-4468-84ee-dfcf536e59f7)

4. Some common parameter error messages, all from
[Marshmallow](https://marshmallow.readthedocs.io/en/stable/marshmallow.fields.html)

Parameter validation configuration
```
    kb_id = fields.String(required=True)
    parser_id = fields.String(validate=validators.OneOf([parser_type.value for parser_type in ParserType]),
                              allow_none=True)
```

When my parameter is
```
kb_id=None,
parser_id='A4'
```

Error messages
```
{
    "detail": {
        "json": {
            "kb_id": [
                "Field may not be null."
            ],
            "parser_id": [
                "Must be one of: presentation, laws, manual, paper, resume, book, qa, table, naive, picture, one, audio, email, knowledge_graph."
            ]
        }
    },
    "message": "Validation error"
}
```

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

### What problem does this PR solve?

fixed /datasets/retrieval API:
KeyError('size') and 'doc_ids': ['Field may not be null.']

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)