output failed tuples to stderr

[senojj]

By writing failed tuples to stderr, they can be collected into a file to be run again in a subsequent write command.

The expectation is to be able to call the CLI like:

fga tuple write --store-id=01H0H015178Y2V4CX10C2KGHF4 --file tuples.csv 2> failed_tuples.csv > result.json

Then it is simple to retry all failed tuples like:

fga tuple write --store-id=01H0H015178Y2V4CX10C2KGHF4 --file failed_tuples.csv

It may also be beneficial to allow the specification of an output format (e.g. json, csv, yaml).