copy_array panics on offset overflow instead of returning an error

[andygrove]

Describe the bug

The arrow 59 migration moved MutableArrayData::extend to the fallible try_extend, but copy_array turns the error straight back into a panic:

native/core/src/execution/operators/copy.rs:42 and :57

mutable
    .try_extend(0, 0, capacity)
    .expect("extend failed due to offset overflow");

Both callers are already in Result context, so an offset overflow aborts the JVM instead of failing the task, which is exactly what arrow deprecated extend for.

Expected behavior

copy_array returns Result<ArrayRef> and the two call sites propagate, turning an offset overflow into a task failure.

Additional context

Found while reviewing #5262.

[andygrove]

Tracked under #5709 ([EPIC] DataFusion 55 upgrade follow-ups).