columnStatistics.minExpr and maxExpr is useful when we derive stats for cast function.
This pr
1. maintains the min/max expr during stats derive in filter condition: col<literal, col>literal and col=literal
2. adjust column stats range for cast function (now only support cast from string to other types)
ds9 is changed, but no performance issue: on tpcds_sf100_rf exe time is 1.5~1.6sec, the same as master
138e6c2f01