Support a constant in a window specification

A query may attempt to generate a function/aggregate with a window specification.

Currently, Impala does not support a constant in the specification. Similarly it may also fail if an expression is generated which via constant folding becomes a constant.

Potentially an application may have to trigger dynamic expressions which participate in a window specification. It may not know that a value-expression that is generated might be constant folded and disallowed. Hence, while it may attempt to decompose when it knows a literal is being used cannot guard for all cases

Error: [Simba][ImpalaJDBCDriver](500051) ERROR processing query/statement. Error Code: 0, SQL state: TStatus(statusCode:ERROR_STATUS, sqlState:HY000, errorMessage:AnalysisException: Expressions in the PARTITION BY clause must not be constant: upper('a') (in sum(qty) OVER (PARTITION BY upper('a')))
), Query: SELECT
`sno` AS `c1`,
SUM(`qty`)
OVER(
PARTITION BY
upper('a')
) AS `c2`
FROM `cert`.`tsupply`.
SQLState: HY000
ErrorCode: 500051

vs

SELECT
`sno` AS `c1`,
SUM(`qty`)
OVER(
PARTITION BY
upper(concat(`sno`,''))
) AS `c2`
FROM `cert`.`tsupply`