write_csv/json/parquet isn't cancel safe

[DDtKey]

Describe the bug

DataFrame::write_csv/json/parquet isn't cancelling safe due to spawned tasks. See these lines: https://github.com/apache/arrow-datafusion/blob/master/datafusion/core/src/physical_plan/file_format/csv.rs#L300-L307

It's actually bad because impossible to wrap such functions to timeout or select! for example.

To Reproduce
Wrap it to select or timeout and check that spawned tasks are still working after cancelling by another branch.

Expected behavior

It should be safe-to-cancel these methods.

Additional context

Possible ways to fix:

1. Use stop/cancel token/channel to stop spawned task on drop of outside variable. Like these: CancellationToken(with drop-guard) or stop-token
2. Wrap spawned tasks(i.e JoinHandle) to future with Drop and call abort for them.

Not sure if there are any other spawns which should be covered as well.

[DDtKey]

I can prepare PR to cover this issue if nobody don't mind / already on it 🙂