pick from master #36316
expression cast( xx as decimal )'s datatype maybe decimalv3 or decimalv2
depending on enable_decimal_conversion value in fe conf file. if
enable_decimal_conversion is true, the datatype is decimalv3(9, 0), but
the datatype was decimalv3(38, 9) in 2.0 releases. So this pr change the
datatype same as 2.0 releases to keep the behavior consistent.
This pr makes three changes to the display of complex types：
1. NULL value in complex types refers to being displayed as `null`, not `NULL`
2. struct type is displayed as "column_name": column_value
3. Time types such as `datetime` and `date`, are displayed with double quotes in complex types. like
`{1, "2023-10-26 12:12:12"}`
This pr also do a code refactor:
1. nesting_level is set to a member variable of the `DataTypeSerDe`, rather than a parameter in methods.
What's more, this pr fix a bug that fileSize is not correct, introduced by this pr: #25854
