[FEA] Support unary operators in Parquet row group and page filtering

[mhaseeb123]

Is your feature request related to a problem? Please describe.
Currently, we only support binary operators such as >, <, == to filter Parquet row groups and data pages. We would now like to extend our parquet filtering to unary operators such as IS_NULL. Currently, using a unary operator in the AST expression leads to a runtime error in the predicate pushdown code (first occurrence: stats based row group filtering).

Describe the solution you'd like

• Pass through unary operators through current Parquet predicate pushdown filters without throwing an error (PR Passthrough unary ops through Parquet predicate pushdown #20127)
• Support common unary operators such as IS_NULL in Parquet predicate pushdown (PR Evaluate IS_NULL at row group and page level in Parquet filtering #20144)

Describe alternatives you've considered
Pre-processing the AST expression to not use unary operators during read_parquet and apply the remaining filters post-read

Additional context
Helps Velox