JsonSetter.contentNulls propagates unexpectedly into nested structures

### Search before asking

- [x] I searched in the [issues](https://github.com/FasterXML/jackson-databind/issues) and found nothing similar.

### Describe the bug

`JsonSetter.contentNulls` should fundamentally only apply to the explicitly provided parameters.
That is, if this specification is applied to a parameter like `List>`, `[null]` should be rejected, but `[[null]]` should be allowed.

However, in practice, `[[null]]` is rejected.

### Version Information

3.1.0

### Reproduction

```java
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
import static org.junit.jupiter.api.Assertions.assertThrows;

public class Kotlin1064Test {
record Dst(
@JsonSetter(contentNulls = Nulls.FAIL)
List> foo
) {}

@Test
public void test() {
var mapper = JsonMapper.builder().build();

assertThrows(InvalidNullException.class, () -> mapper.readValue("{\"foo\":[null]}", Dst.class));
// fails
assertDoesNotThrow(() -> mapper.readValue("{\"foo\":[[null]]}", Dst.class));
}
}
```

### Expected behavior

_No response_

### Additional context

This relates to the following issues.
https://github.com/FasterXML/jackson-module-kotlin/issues/1064

While it's hard to say what behavior is ideal, having `Nulls.FAIL` applied to the entire nested structure feels a bit cumbersome to handle.

Also, I don't have a specific design in mind yet, but I feel that fundamentally, we might need to change the structure of `JsonSetter`.