Remove support for `List` types in `bit_length` kernel

[Jefffrey]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

arrow-rs/arrow-string/src/length.rs

Lines 111 to 131 in 7291147

	/// Returns an array of Int32/Int64 denoting the number of bits in each value in the array.
	///
	/// * this only accepts StringArray/Utf8, LargeString/LargeUtf8, BinaryArray and LargeBinaryArray,
	/// or DictionaryArray with above Arrays as values
	/// * bit_length of null is null.
	/// * bit_length is in number of bits
	pub fn bit_length(array: &dyn Array) -> Result<ArrayRef, ArrowError> {
	if let Some(d) = array.as_any_dictionary_opt() {
	let lengths = bit_length(d.values().as_ref())?;
	return Ok(d.with_values(lengths));
	}
	match array.data_type() {
	DataType::List(_) => {
	let list = array.as_list::<i32>();
	Ok(bit_length_impl::<Int32Type>(list.offsets(), list.nulls()))
	}
	DataType::LargeList(_) => {
	let list = array.as_list::<i64>();
	Ok(bit_length_impl::<Int64Type>(list.offsets(), list.nulls()))
	}

The bit_length kernel documentation states it is only for strings, and the way it calculates bit length for lists assumes each element in a list = 1 byte. I think this may have been a mistake, and we should remove this handling for clarity.

Describe the solution you'd like

Remove support for List types in bit_length kernel.

Describe alternatives you've considered

Keep this behaviour since it's been like this for a while now and might be considered breaking behaviour change

Additional context

Seems it was introduced by

• Cleanup length and bit_length kernels #4718