Consolidate the Scala "cannot fail" checks: arrays.cannotThrow and QueryPlanSerde.cannotFail #7585

What is the problem the feature request solves?

Comet's Scala side has more than one answer to "can evaluating this expression raise an error?":

• cannotThrow in arrays.scala admits only a Literal, Attribute or BoundReference. CometArrayAppend uses it to decide whether the item can be evaluated for a row Spark would not evaluate it on:

  datafusion-comet/spark/src/main/scala/org/apache/comet/serde/arrays.scala

  Lines 86 to 89 in 8f4ce5e

  	private def cannotThrow(expr: Expression): Boolean = expr match {
  	case _: Literal | _: Attribute | _: BoundReference => true
  	case _ => false
  	}

• QueryPlanSerde.cannotFail, added in fix: fall back TopK whose later sort key can fail under ANSI #7457 , answers the same question for TopK's later sort keys with a wider list (non-ANSI arithmetic, some string functions, casts through CometCast.cannotFail).
• feat: run filter and exists lambdas natively with DataFusion's higher-order functions #7322 adds a third list, NativeLambdaSerde.mayRaise, for native lambdas, and Native lambdas: count a widening cast as unable to raise under ANSI mode #7535 already tracks a case where it is stricter than it needs to be.

Each copy has to be widened or tightened on its own, so a fix to one (for example a new cast that cannot fail, or a kernel found to raise where Spark does not) is easy to miss in the others.

Describe the potential solution

Keep one Scala notion of an expression that cannot fail, QueryPlanSerde.cannotFail, and have arrays.scala (and NativeLambdaSerde.mayRaise, if #7322 lands first) call it instead of keeping its own list.

This widens when array_append runs natively, so the change needs its own tests for the newly admitted item expressions, including ones that fail under ANSI.

Additional context

Raised in the review of #7457 :

• fix: fall back TopK whose later sort key can fail under ANSI #7457 (comment)
• fix: fall back TopK whose later sort key can fail under ANSI #7457 (review)

Willingness to contribute

I can contribute a fix for this bug independently