[pixels-core] date column writer produces the wrong date number

[yuly16]

Reproduce the issue:

First, we create a table with a date column, the filename is test_date.tbl. The file only contains 6 rows:

We call pixels-sink to generate test_date.pxl file, and then use trino:

The date in test_date.pxl is different from test_date.tbl.

The problematic function is millisToDay in DatetimeUtils.java. When writing the date to pxl file, millisToDay is responsible for translating Date to int. The scratch date is 1970-01-01. However, I notice that this function translates 1970-01-02 to 0, while the correct anwser should be 1.

[bianhq]

Fixed.