`stageIn/OutMode = *` options

## New feature

Hi,

Would you be able to add a new config option that let's us tweak the `cp`/`rsync`/`rclone` options during staging in/out

## Use case 

Speeding up transfers where possible, for example using better compression for `rsync` (`--zc=zstd`) 


## Suggested implementation 

New config option which gets translated to the `.command.run` script
