Fix between for DECIMAL columns with certain literal values in projection.

With the code at cc6c51b5 the test fails:

DROP TABLE cs1;

CREATE TABLE cs1 (d1 DECIMAL(38))engine=columnstore;

INSERT INTO cs1 VALUES (123456);

SELECT "between_test", d1 BETWEEN 123455 AND 123457 f1 FROM cs1;

This happens b/c of the error introduced by the recent decimal comparison refactoring.
The patch also addresses the fact that ConstantColumn() creates fResult.decimalVal as a narrow decimal for literals 123455 and 123457 b/c MDB sends the literals as an INTs and not wide-DECIMALs.