Bug fix: ClientProvider not set connection to calendar and instrument provider when initializing.

[chaosddp]

The isinstance checking for client calendar and client instrument provider are not correct, here is a little patch to fix it.

And fix the dump script to drop duplicates.

Description

When use qlib online mode, with following configuration (from qlib-server document), will cause exception "qlib/data/data.py", line 817, in list_instruments. AttributeError: 'NoneType' object has no attribute 'send_request'".

calendar_provider:
  class: LocalCalendarProvider
  kwargs:
    remote: True

feature_provider:
  class: LocalFeatureProvider
  kwargs:
    remote: True

instrument_provider: ClientInstrumentProvider

expression_provider: LocalExpressionProvider

dataset_provider: ClientDatasetProvider

provider: ClientProvider

expression_cache: null
dataset_cache: null
calendar_cache: null

Motivation and Context

How Has This Been Tested?

• Pass the test by running: pytest qlib/tests/test_all_pipeline.py under upper directory of qlib.
• If you are adding a new feature, test on your own test scripts.

Screenshots of Test Results (if appropriate):

1. Pipeline test:
2. Your own tests:

Types of changes

• Fix bugs
• Add new feature
• Update documentation

[you-n-g]

@chaosddp

It looks great!
Thanks so much!