`abs` on interval types falls back to Spark

[andygrove]

Part of #5572.

abs on an interval falls the whole projection back to Spark:

case _: NumericType =>
  Compatible()
case _ =>
  // Spark supports NumericType, DayTimeIntervalType, and YearMonthIntervalType
  Unsupported(Some(unsupportedReason))

spark/src/main/scala/org/apache/comet/serde/math.scala:178-184

The comment already names the gap. docs/source/user-guide/latest/expressions.md records it as "Interval types fall back".

Both interval families are explicitly supported by the dispatcher's type surface:

case _: YearMonthIntervalType | _: DayTimeIntervalType | CalendarIntervalType => true

spark/src/main/scala/org/apache/comet/codegen/CometBatchKernelCodegen.scala:92

so canHandle admits abs(interval_col) and Spark's own doGenCode gives the ANSI overflow behavior for Long.MinValue micros for free — which is worth having, since that is exactly the edge a native implementation would need to get right.

Fix: mix CodegenDispatchFallback into CometAbs.

[kazantsev-maksim]

take