Update index_data.py for datatype conversion and alignment

[taozhiwang]

Description

Hi,

Here I change index_data.py for converting time in datetime64 into the same precision with user data. This helps users avoid query failures due to precision issues.

Datetype detection is performed during initialization to avoid inconsistencies in the format of user data. This may have some impact on efficiency.

Changed files:

1. index_data.py change __init__ under Index for the initial alignment test, also change _convert_type for detecting data type and convert precision
2. test_index_data.py test above changes
3. shrink.py pre-commit auto-correction

Motivation and Context

issue 1806

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:

3. Your own tests:

Types of changes

• Fix bugs
• Add new feature
• Update documentation

[taozhiwang]

@microsoft-github-policy-service agree

[you-n-g]

Thanks for your great efforts.