Add support for Timestamp data type in SQL Select (#7185)

This change adds support for casting strings to Timestamp via CAST:
`CAST('2010T' AS TIMESTAMP)`

It also implements the following date-time functions:
  - UTCNOW()
  - DATE_ADD()
  - DATE_DIFF()
  - EXTRACT()

For values passed to these functions, date-types are automatically
inferred.

pkg/s3select/sql/evaluate.go

@@ -305,10 +305,9 @@ func (e *UnaryTerm) evalNode(r Record) (*Value, error) {
 	}
 
 	inferTypeForArithOp(v)
-	if ival, ok := v.ToInt(); ok {
-		return FromInt(-ival), nil
-	} else if fval, ok := v.ToFloat(); ok {
-		return FromFloat(-fval), nil
+	v.negate()
+	if v.isNumeric() {
+		return v, nil
 	}
 	return nil, errArithMismatchedTypes
 }