fixing the single quoted literal in window function

[xiangfu0]

When literal arguments are singled quoted, it's parsed to WindowNode inputs, as a literal, not constants.

Sample query:

WITH tmp AS (
  select count(*) as num_trips,
    DaysSinceEpoch
  from airlineStats
  GROUP BY DaysSinceEpoch
)

SELECT DaysSinceEpoch,
  num_trips,
  LAG(num_trips, '2') OVER (
    ORDER BY DaysSinceEpoch
  ) AS previous_num_trips,
  num_trips - LAG(num_trips, '2') OVER (
    ORDER BY DaysSinceEpoch
  ) AS difference
FROM tmp;

Before:

Caused by: java.lang.IllegalArgumentException: Second operand (offset) of LAG function must be a literal
	at com.google.common.base.Preconditions.checkArgument(Preconditions.java:145)
	at org.apache.pinot.query.runtime.operator.window.value.LagValueWindowFunction.<init>(LagValueWindowFunction.java:43)
	... 24 more

After: