Implement RecordBatch::slice() to slice RecordBatches

[alamb]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
When implementing an operator that needed to check for partitions across RecordBatch boundaries (in https://github.com/influxdata/influxdb_iox/pull/1733) I found myself wanting to slice the record batch so I could keep part of it while I sent the rest through

In addition I can imagine an operator like RepartitionExec which might want to break large batches into smaller batches when repartitioning.

Describe the solution you'd like
Implement the following function

impl RecordBatch { .
...
  /// Return a new RecordBatch where each column is sliced
  /// according to `offset` and `length`
  pub fn::slice(fn slice(&self, offset: usize, length: usize) -> Result<RecordBatch> {
  }

There is already a Array::slice method: https://github.com/apache/arrow-rs/blob/master/arrow/src/array/array.rs#L83-L98 so to slice a RecordBatch you simply apply that function to each column

Here is a partial implementation, from https://github.com/influxdata/influxdb_iox/pull/1733

    fn concat_record_batches(batches: &[RecordBatch]) -> ArrowResult<RecordBatch> {
        assert!(!batches.is_empty());

        // concatenate them column by column
        let schema = batches[0].schema();
        let num_columns = batches[0].columns().len();
        let new_columns = (0..num_columns)
            .map(|column_index| {
                let old_columns: Vec<_> = batches
                    .iter()
                    .map(|batch| batch.column(column_index).as_ref())
                    .collect();
                arrow::compute::concat(&old_columns)
            })
            .collect::<ArrowResult<Vec<_>>>()?;

        RecordBatch::try_new(schema, new_columns)

Describe alternatives you've considered

RecordBatch::split is proposed in #343 but slice may be more general (and work better with existing Rust API ecosystem)

Additional context
Add any other context or screenshots about the feature request here.

[b41sh]

Can I take this one?

[alamb]

@b41sh yes please! I will assign it to you